A preposition links nouns, pronouns and phrases to other words in a sentence. The word or phrase that the preposition introduces is called the object of the preposition.
A preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence as in the following examples:
The book is *on the table.
The book is *beneath the table.
The book is leaning *against the table.
The book is *beside the table.
She held the book *over the table.
She read the book *during class.
In each of the preceding sentences, a preposition locates the noun "book" in space or in time.
A prepositional phrase is made up of the preposition, its object and any associated adjectives or adverbs. A prepositional phrase can function as a noun, an adjective, or an adverb. The most common prepositions are "about," "above," "across," "after," "against," "along," "among," "around," "at," "before," "behind," "below," "beneath," "beside," "between," "beyond," "but," "by," "despite," "down," "during," "except," "for," "from," "in," "inside," "into," "like," "near," "of," "off," "on," "onto," "out," "outside," "over," "past," "since," "through," "throughout," "till," "to," "toward," "under," "underneath," "until," "up," "upon," "with," "within," and "without."
Each of the * words in the following sentences is a preposition:
The children climbed the mountain *without fear.
In this sentence, the preposition "without" introduces the noun "fear." The prepositional phrase "without fear" functions as an adverb describing how the children climbed.
There was rejoicing *throughout the land when the government was defeated.
Here, the preposition "throughout" introduces the noun phrase "the land." The prepositional phrase acts as an adverb describing the location of the rejoicing.
The spider crawled slowly *along the banister.
The preposition "along" introduces the noun phrase "the banister" and the prepositional phrase "along the banister" acts as an adverb, describing where the spider crawled.
The dog is hiding *under the porch because it knows it will be punished for chewing up a new pair of shoes.
Here the preposition "under" introduces the prepositional phrase "under the porch," which acts as an adverb modifying the compound verb "is hiding."
The screenwriter searched for the manuscript he was certain was somewhere *in his office.
Similarly in this sentence, the preposition "in" introduces a prepositional phrase "in his office," which acts as an adverb describing the location of the missing papers
A noun is a word used to name a person, animal, place, thing, and abstract idea. Nouns are usually the first words which small children learn. The * words in the following sentences are all nouns:
Late last year our neighbours bought a *goat.
Portia White was an opera *singer.
The bus inspector looked at all the passengers' passes.
According to Plutarch, the library at *Alexandria was destroyed in 48 B.C.
Philosophy is of little comfort to the *starving.
A noun can function in a sentence as a subject, a direct object, an indirect object, a subject complement, an object complement, an appositive, an adjective or an adverb.
Many common nouns, like "engineer" or "teacher," can refer to men or women. Once, many English nouns would change form depending on their gender -- for example, a man was called an "author" while a woman was called an "authoress" -- but this use of gender-specific nouns is very rare today. Those that are still used occasionally tend to refer to occupational categories, as in the following sentences.
David Garrick was a very prominent eighteenth-century actor.
Sarah Siddons was at the height of her career as an actress in the 1780s.
The manager was trying to write a want ad, but he couldn't decide whether he was advertising for a "waiter" or a "waitress"
Most nouns change their form to indicate number by adding "-s" or "-es", as illustrated in the following pairs of sentences:
When Matthew was small he rarely told the *truth if he thought he was going to be punished.
Many people do not believe that *truths are self-evident.
As they walked through the silent house, they were startled by an unexpected *echo.
I like to shout into the quarry and listen to the *echoes that return.
He tripped over a *box left carelessly in the hallway.
Since we are moving, we will need many *boxes.
There are other nouns which form the plural by changing the last letter before adding "s". Some words ending in "f" form the plural by deleting "f" and adding "ves," and words ending in "y" form the plural by deleting the "y" and adding "ies," as in the following pairs of sentences:
The *harbour at Marble Mountain has one wharf.
There are several wharves in Halifax *Harbour.
Warsaw is their favourite *city because it reminds them of their courtship.
The vacation my grandparents won includes trips to twelve European *cities.
The children circled around the headmaster and shouted, "Are you a *mouse or a man?"
The audience was shocked when all five men admitted that they were afraid of *mice.
Other nouns form the plural irregularly. If English is your first language, you probably know most of these already: when in doubt, consult a good dictionary.
In the possessive case, a noun or pronoun changes its form to show that it owns or is closely related to something else. Usually, nouns become possessive by adding a combination of an apostrophe and the letter "s."
You can form the possessive case of a singular noun that does not end in "s" by adding an apostrophe and "s," as in the following sentences:
The red suitcase is *Cassandra's.
The only luggage that was lost was the prime minister's.
The exhausted recruits were woken before dawn by the drill sergeant's screams.
The *miner's face was covered in coal dust.
You can form the possessive case of a singular noun that ends in "s" by adding an apostrophe alone or by adding an apostrophe and "s," as in the following examples:
The *bus's seats are very uncomfortable.
The *bus' seats are very uncomfortable.
The film crew accidentally crushed the *platypus's eggs.
The film crew accidentally crushed the *platypus' eggs.
Felicia Hemans's poetry was once more popular than Lord Byron's.
Felicia Hemans' poetry was once more popular than Lord Byron's.
You can form the possessive case of a plural noun that does not end in "s" by adding an apostrophe and a "s," as in the following examples:
The *children's mittens were scattered on the floor of the porch.
The *sheep's pen was mucked out every day.
Since we have a complex appeal process, a *jury's verdict is not always final.
The *men's hockey team will be playing as soon as the women's team is finished.
The hunter followed the *moose's trail all morning but lost it in the afternoon.
You can form the possessive case of a plural noun that does end in "s" by adding an apostrophe:
The concert was interrupted by the dogs' barking, the ducks' quacking, and the *babies' squalling.
The *janitors' room is downstairs and to the left.
My uncle spent many hours trying to locate the *squirrels' nest.
The archivist quickly finished repairing the *diaries' bindings.
Religion is usually the subject of the *roommates' many late night debates.
USING POSSESSIVE NOUNS
When you read the following sentences, you will notice that a noun in the possessive case frequently functions as an adjective modifying another noun:
The *miner's face was covered in coal dust.
Here the possessive noun "miner's" is used to modify the noun "face" and together with the article "the," they make up the noun phrase that is the sentence's subject.
The concert was interrupted by the dogs' barking, the ducks' quacking, and the *babies' squalling.
In this sentence, each possessive noun modifies a gerund. The possessive noun "dogs"' modifies "barking," "ducks"' modifies "quacking," and "babies"' modifies "squalling."
The film crew accidentally crushed the *platypus's eggs.
In this example the possessive noun "platypus's" modifies the noun "eggs" and the noun phrase "the platypus's eggs" is the direct object of the verb "crushed."
My uncle spent many hours trying to locate the *squirrels' nest.
In this sentence the possessive noun "squirrels"' is used to modify the noun "nest" and the noun phrase "the squirrels' nest" is the object of the infinitive phrase "to locate."
TYPES OF NOUNS
There are many different types of nouns. As you know, you capitalise some nouns, such as "Canada" or "Louise," and do not capitalise others, such as "badger" or "tree" (unless they appear at the beginning of a sentence). In fact, grammarians have developed a whole series of noun types, including the proper noun, the common noun, the concrete noun, the abstract noun, the countable noun (also called the count noun), the non-countable noun (also called the mass noun), and the collective noun. You should note that a noun will belong to more than one type: it will be proper or common, abstract or concrete, and countable or non-countable or collective.
If you are interested in the details of these different types, you can read about them in the following sections.
You always write a proper noun with a capital letter, since the noun represents the name of a specific person, place, or thing. The names of days of the week, months, historical documents, institutions, organisations, religions, their holy texts and their adherents are proper nouns. A proper noun is the opposite of a common noun
In each of the following sentences, the proper nouns are *:
The Marroons were transported from Jamaica and forced to build the fortifications in *Halifax.
Many people dread *Monday mornings.
Beltane is celebrated on the first of May.
Abraham appears in the Talmud and in the *Koran.
Last year, I had a Baptist, a Buddhist, and a Gardnerian Witch as roommates.
A common noun is a noun referring to a person, place, or thing in a general sense -- usually, you should write it with a capital letter only when it begins a sentence. A common noun is the opposite of a proper noun.
In each of the following sentences, the common nouns are *:
According to the sign, the nearest town is 60 *miles away.
All the gardens in the neighbourhood were invaded by beetles this summer.
I don't understand why some people insist on having six different kinds of mustard in their cupboards.
The road crew was startled by the sight of three large moose crossing the road.
Many child-care workers are *underpaid.
Sometimes you will make proper nouns out of common nouns, as in the following examples:
The tenants in the *Garnet Apartments are appealing the large and sudden increase in their rent.
The meals in the *Bouncing Bean Restaurant are less expensive than meals in ordinary restaurants.
Many witches refer to the Renaissance as the Burning *Times.
The Diary of Anne Frank is often a child's first introduction to the history of the Holocaust.
A concrete noun is a noun which names anything (or anyone) that you can perceive through your physical senses: touch, sight, taste, hearing, or smell. A concrete noun is the opposite of a abstract noun.
The * words in the following sentences are all concrete nouns:
The judge handed the files to the *clerk.
Whenever they take the dog to the beach, it spends hours chasing *waves.
The real estate agent urged the couple to buy the second house because it had new shingles.
As the car drove past the park, the thump of a disco tune overwhelmed the string quartet's rendition of a *minuet.
The book binder replaced the flimsy paper cover with a sturdy, cloth-covered board.
An abstract noun is a noun which names anything which you can not perceive through your five physical senses, and is the opposite of a concrete noun. The * words in the following sentences are all abstract nouns:
Buying the fire extinguisher was an *afterthought.
Tillie is amused by people who are nostalgic about *childhood.
*Justice often seems to slip out of our grasp.
Some scientists believe that *schizophrenia is transmitted genetically.
A countable noun (or count noun) is a noun with both a singular and a plural form, and it names anything (or anyone) that you can count. You can make a countable noun plural and attach it to a plural verb in a sentence. Countable nouns are the opposite of non-countable nouns and collective nouns.
In each of the following sentences, the * words are countable nouns:
We painted the table red and the chairs blue.
Since he inherited his aunt's library, Jerome spends every weekend indexing his books.
Miriam found six silver dollars in the toe of a *sock.
The oak tree lost three branches in the *hurricane.
Over the course of twenty-seven years, Martha Ballad delivered just over eight hundred *babies.
A non-countable noun (or mass noun) is a noun which does not have a plural form, and which refers to something that you could (or would) not usually count. A non-countable noun always takes a singular verb in a sentence. Non-countable nouns are similar to collective nouns, and are the opposite of countable nouns.
The * words in the following sentences are non-countable nouns:
Joseph Priestly discovered *oxygen.
The word "oxygen" cannot normally be made plural.
*Oxygen is essential to human life.
Since "oxygen" is a non-countable noun, it takes the singular verb "is" rather than the plural verb "are."
We decided to sell the *furniture rather than take it with us when we moved.
You cannot make the noun "furniture" plural.
The *furniture is heaped in the middle of the room.
Since "furniture" is a non-countable noun, it takes a singular verb, "is heaped."
The crew spread the *gravel over the roadbed.
You cannot make the non-countable noun "gravel" plural.
*Gravel is more expensive than I thought.
Since "gravel" is a non-countable noun, it takes the singular verb form "is."
A collective noun is a noun naming a group of things, animals, or persons. You could count the individual members of the group, but you usually think of the group as a whole is generally as one unit. You need to be able to recognise collective nouns in order to maintain subject-verb agreement. A collective noun is similar to a non-countable noun, and is roughly the opposite of a countable noun.
In each of the following sentences, the * word is a collective noun:
The *flock of geese spends most of its time in the pasture.
The collective noun "flock" takes the singular verb "spends."
The *jury is dining on take-out chicken tonight.
In this example the collective noun "jury" is the subject of the singular compound verb "is dining."
The steering *committee meets every Wednesday afternoon.
Here the collective noun "committee" takes a singular verb, "meets."
The *class was startled by the bursting light bulb.
In this sentence the word "class" is a collective noun and takes the singular compound verb "was startled."
A pronoun can replace a noun or another pronoun. You use pronouns like "he," "which," "none," and "you" to make your sentences less cumbersome and less repetitive.
Grammarians classify pronouns into several types, including the personal pronoun, the demonstrative pronoun, the interrogative pronoun, the indefinite pronoun, the relative pronoun, the reflexive pronoun, and the intensive pronoun.
A personal pronoun refers to a specific person or thing and changes its form to indicate person, number, gender, and case.
SUBJECTIVE PERSONAL PRONOUNS
A subjective personal pronoun indicates that the pronoun is acting as the subject of the sentence. The subjective personal pronouns are "I," "you," "she," "he," "it," "we," "you," "they."
*I was glad to find the bus pass in the bottom of the green knapsack.
You are surely the strangest child I have ever met.
*He stole the selkie's skin and forced her to live with him.
When she was a young woman, she earned her living as a coal miner.
After many years, *they returned to their homeland.
OBJECTIVE PERSONAL PRONOUNS
An objective personal pronoun indicates that the pronoun is acting as an object of a verb, compound verb, preposition, or infinitive phrase. The objective personal pronouns are: "me," "you," "her," "him," "it," "us," "you," and "them."
Seamus stole the selkie's skin and forced her to live with him.
The objective personal pronoun "her" is the direct object of the verb "forced" and the objective personal pronoun "him" is the object of the preposition "with."
After reading the pamphlet, Judy threw *it into the garbage can.
The pronoun "it" is the direct object of the verb "threw."
The agitated assistant stood up and faced the angry delegates and said, "Our leader will address *you in five minutes."
In this sentence, the pronoun "you" is the direct object of the verb "address."
POSSESSIVE PERSONAL PRONOUNS
A possessive pronoun indicates that the pronoun is acting as a marker of possession and defines who owns a particular object or person. The possessive personal pronouns are "mine," "yours," "hers," "his," "its," "ours," and "theirs." Note that possessive personal pronouns are very similar to possessive adjectives like "my," "her," and "their."
The smallest gift is *mine.
Here the possessive pronoun "mine" functions as a subject complement.
This is *yours.
Here too the possessive pronoun "yours" functions as a subject complement.
A demonstrative pronoun points to and identifies a noun or a pronoun. "This" and "these" refer to things that are nearby either in space or in time, while "that" and "those" refer to things that are farther away in space or time.
The demonstrative pronouns are "this," "that," "these," and "those." "This" and "that" are used to refer to singular nouns or noun phrases and "these" and "those" are used to refer to plural nouns and noun phrases. Note that the demonstrative pronouns are identical to demonstrative adjectives, though, obviously, you use them differently. It is also important to note that "that" can also be used as a relative pronoun.
*This must not continue.
Here "this" is used as the subject of the compound verb "must not continue."
This is puny; that is the tree I want.
In this example "this" is used as subject and refers to something close to the speaker. The demonstrative pronoun "that" is also a subject but refers to something farther away from the speaker.
An interrogative pronoun is used to ask questions. The interrogative pronouns are "who," "whom," "which," "what" and the compounds formed with the suffix "ever" ("whoever," "whomever," "whichever," and "whatever"). Note that either "which" or "what" can also be used as an interrogative adjective, and that "who," "whom," or "which" can also be used as a relative pronoun.
You will find "who," "whom," and occasionally "which" used to refer to people, and "which" and "what" used to refer to things and to animals.
"Who" acts as the subject of a verb, while "whom" acts as the object of a verb, preposition, or a verbal.
The highlighted word in each of the following sentences is an interrogative pronoun:
Which wants to see the dentist first?
"Which" is the subject of the sentence.
You can use a relative pronoun is used to link one phrase or clause to another phrase or clause. The relative pronouns are "who," "whom," "that," and "which." The compounds "whoever," "whomever," and "whichever" are also relative pronouns.
You can use the relative pronouns "who" and "whoever" to refer to the subject of a clause or sentence, and "whom" and "whomever" to refer to the objects of a verb, a verbal or a preposition.
In each of the following sentences, the highlighted word is a relative pronoun.
You may invite whomever you like to the party.
The relative pronoun "whomever" is the direct object of the compound verb "may invite."
An indefinite pronoun is a pronoun referring to an identifiable but not specified person or thing. An indefinite pronoun conveys the idea of all, any, none, or some.
The most common indefinite pronouns are "all," "another," "any," "anybody," "anyone," "anything," "each," "everybody," "everyone," "everything," "few," "many," "nobody," "none," "one," "several," "some," "somebody," and "someone." Note that some indefinite pronouns can also be used as indefinite adjectives.
The highlighted words in the following sentences are indefinite pronouns:
Many were invited to the lunch but only twelve showed up.
Here "many" acts as the subject of the compound verb "were invited."
You can use a reflexive pronoun to refer back to the subject of the clause or sentence.
The reflexive pronouns are "myself," "yourself," "herself," "himself," "itself," "ourselves," "yourselves," and "themselves." Note each of these can also act as an intensive pronoun.
Each of the highlighted words in the following sentences is a reflexive pronoun:
Diabetics give themselves insulin shots several times a day.
The Dean often does the photocopying herself so that the secretaries can do more important work.
After the party, I asked myself why I had faxed invitations to everyone in my office building.
Richard usually remembered to send a copy of his e-mail to himself.
Although the landlord promised to paint the apartment, we ended up doing it ourselves.
An intensive pronoun is a pronoun used to emphasise its antecedent. Intensive pronouns are identical in form to reflexive pronouns.
The highlighted words in the following sentences are intensive pronouns:
I myself believe that aliens should abduct my sister.
The Prime Minister himself said that he would lower taxes.
They themselves promised to come to the party even though they had a final exam at the same time.
An adjective is a word that gives more information about a noun or pronoun. An adverb is usually defined as a word that gives more information about a verb, an adjective or another adverb. Adverbs describe verbs, adjectives and adverbs in terms of such qualities as time, frequency and manner. Usually answer one of these questions: When? Where? How? Why? Under what conditions? How often? To what degree? In the sentence Sue runs fast, fast describes how or the manner in which Sue runs. In the sentence Sue runs very fast, very describes the adverb fast and gives information about how fast Sue runs.
Most, but not all adverbs end in -ly as in But not all words that end in -ly are adverbs (ugly is an adjective, supply and reply can both be nouns or verbs). Many times an adjective can be made into an adverb by adding -ly as in nicely, quickly, completely, sincerely.
beautiful........more beautiful.......most beautiful
Use comparative to compare two things, superlative to compare 3 or more.
Which of these two brands of toothpaste is (better\best)?
An adjective modifies a noun or a pronoun by describing, identifying, or quantifying words. An adjective usually precedes the noun or the pronoun which it modifies.
In the following examples, the highlighted words are adjectives:
The truck-shaped balloon floated over the treetops.
Mrs. Morrison papered her kitchen walls with hideous wall paper.
The small boat foundered on the wine dark sea.
The coal mines are dark and dank.
Many stores have already begun to play irritating Christmas music.
A battered music box sat on the mahogany sideboard.
The back room was filled with large, yellow rain boots.
An adjective can be modified by an adverb, or by a phrase or clause functioning as an adverb. In the sentence
My husband knits intricately patterned mittens.
for example, the adverb "intricately" modifies the adjective "patterned."
Some nouns, many pronouns, and many participle phrases can also act as adjectives. In the sentence
Eleanor listened to the muffled sounds of the radio hidden under her pillow.
for example, both highlighted adjectives are past participles.
Grammarians also consider articles ("the," "a," "an") to be adjectives.
A possessive adjective ("my," "your," "his," "her," "its," "our," "their") is similar or identical to a possessive pronoun; however, it is used as an adjective and modifies a noun or a noun phrase, as in the following sentences:
I can't complete my assignment because I don't have the textbook.
In this sentence, the possessive adjective "my" modifies "assignment" and the noun phrase "my assignment" functions as an object. Note that the possessive pronoun form "mine" is not used to modify a noun or noun phrase.
What is your phone number.
Here the possessive adjective "your" is used to modify the noun phrase "phone number"; the entire noun phrase "your phone number" is a subject complement. Note that the possessive pronoun form "yours" is not used to modify a noun or a noun phrase.
The bakery sold his favourite type of bread.
In this example, the possessive adjective "his" modifies the noun phrase "favourite type of bread" and the entire noun phrase "his favourite type of bread" is the direct object of the verb "sold."
After many years, she returned to her homeland.
Here the possessive adjective "her" modifies the noun "homeland" and the noun phrase "her homeland" is the object of the preposition "to." Note also that the form "hers" is not used to modify nouns or noun phrases.
We have lost our way in this wood.
In this sentence, the possessive adjective "our" modifies "way" and the noun phrase "our way" is the direct object of the compound verb "have lost". Note that the possessive pronoun form "ours" is not used to modify nouns or noun phrases.
In many fairy tales, children are neglected by their parents.
Here the possessive adjective "their" modifies "parents" and the noun phrase "their parents" is the object of the preposition "by." Note that the possessive pronoun form "theirs" is not used to modify nouns or noun phrases.
The cat chased its ball down the stairs and into the backyard.
In this sentence, the possessive adjective "its" modifies "ball" and the noun phrase "its ball" is the object of the verb "chased." Note that "its" is the possessive adjective and "it's" is a contraction for "it is."
The demonstrative adjectives "this," "these," "that," "those," and "what" are identical to the demonstrative pronouns, but are used as adjectives to modify nouns or noun phrases, as in the following sentences:
When the librarian tripped over that cord, she dropped a pile of books.
In this sentence, the demonstrative adjective "that" modifies the noun "cord" and the noun phrase "that cord" is the object of the preposition "over."
This apartment needs to be fumigated.
Here "this" modifies "apartment" and the noun phrase "this apartment" is the subject of the sentence.
Even though my friend preferred those plates, I bought these.
In the subordinate clause, "those" modifies "plates" and the noun phrase "those plates" is the object of the verb "preferred." In the independent clause, "these" is the direct object of the verb "bought."
Note that the relationship between a demonstrative adjective and a demonstrative pronoun is similar to the relationship between a possessive adjective and a possessive pronoun, or to that between a interrogative adjective and an interrogative pronoun.
An interrogative adjective ("which" or "what") is like an interrogative pronoun, except that it modifies a noun or noun phrase rather than standing on its own (see also demonstrative adjectives and possessive adjectives):
Which plants should be watered twice a week?
Like other adjectives, "which" can be used to modify a noun or a noun phrase. In this example, "which" modifies "plants" and the noun phrase "which plants" is the subject of the compound verb "should be watered":
What book are you reading?
In this sentence, "what" modifies "book" and the noun phrase "what book" is the direct object of the compound verb "are reading."
An indefinite adjective is similar to an indefinite pronoun, except that it modifies a noun, pronoun, or noun phrase, as in the following sentences:
Many people believe that corporations are under-taxed.
The indefinite adjective "many" modifies the noun "people" and the noun phrase "many people" is the subject of the sentence.
I will send you any mail that arrives after you have moved to Sudbury.
The indefinite adjective "any" modifies the noun "mail" and the noun phrase "any mail" is the direct object of the compound verb "will send."
They found a few goldfish floating belly up in the swan pound.
In this example the indefinite adjective modifies the noun "goldfish" and the noun phrase is the direct object of the verb "found":
The title of Kelly's favourite game is "All dogs go to heaven."
Here the indefinite pronoun "all" modifies "dogs" and the full title is a subject complement.
The part of speech (or word class) that serves to connect words, phrases, clauses, or sentences.
The common conjunctions--and, but, for, or, nor, yet, and so--join the elements of a coordinate structure.
You use a co-ordinating conjunction ("and," "but," "or," "nor," "for," "so," or "yet") to join individual words, phrases, and independent clauses. Note that you can also use the conjunctions "but" and "for" as prepositions.
In the following sentences, each of the * words is a co-ordinating conjunction:
Lilacs *and violets are usually purple.
In this example, the co-ordinating conjunction "and" links two nouns.
This movie is particularly interesting to feminist film theorists, *for the screenplay was written by Mae West.
In this example, the co-ordinating conjunction "for" is used to link two independent clauses.
A subordinating conjunction introduces a dependent clause and indicates the nature of the relationship among the independent clause(s) and the dependent clause(s).
The most common subordinating conjunctions are "after," "although," "as," "because," "before," "how," "if," "once," "since," "than," "that," "though," "till," "until," "when," "where," "whether," and "while."
Each of the * words in the following sentences is a subordinating conjunction:
*After she had learned to drive, Alice felt more independent.
The subordinating conjunction "after" introduces the dependent clause "After she had learned to drive."
*If the paperwork arrives on time, your cheque will be mailed on Tuesday.
Similarly, the subordinating conjunction "if" introduces the dependent clause "If the paperwork arrives on time."
Gerald had to begin his thesis over again *when his computer crashed.
The subordinating conjunction "when" introduces the dependent clause "when his computer crashed."
Midwifery advocates argue that home births are safer *because the mother and baby are exposed to fewer people and fewer germs.
In this sentence, the dependent clause "because the mother and baby are exposed to fewer people and fewer germs" is introduced by the subordinating conjunction "because."
Correlative conjunctions always appear in pairs -- you use them to link equivalent sentence elements. The most common correlative conjunctions are "both...and," "either...or," "neither...nor,", "not only...but also," "so...as," and "whether...or." (Technically correlative conjunctions consist simply of a co-ordinating conjunction linked to an adjective or adverb.)
The * words in the following sentences are correlative conjunctions:
Both my grandfather and my father worked in the steel plant.
In this sentence, the correlative conjunction "both...and" is used to link the two noun phrases that act as the compound subject of the sentence: "my grandfather" and "my father".