An adverb clause consists of a connecting word, called an adverb clause marker (or subordinate conjunction), and at least a subject and a verb.
The demand for economical cars increases when gasoline becomes more expensive.
In this example, the adverb clause marker when joins the adverb clause to the main clause. The adverb clause contains a subject (gasoline) and a verb (becomes).
An adverb clause can precede the main clause or follow it. When the adverb clause comes first, it is separated from the main clause by a comma.
When gasoline becomes more expensive, the demand for economical cars increases.
The following markers are commonly seen in the Structure section
| Adjective Clause Marker | Use | Example |
| because | cause | Because the speaker was sick, the program was canceled. |
| since | cause | Since credit cards are so convenient, many people use them. |
| although | opposition (contrary cause) | Although he earns a good salary, he never saves any money. |
| even though | opposition (contrary cause) | Even though she was tired, she stayed up late. |
| while | contrast | Some people arrived in taxis while others took the subway. |
| if | condition | If the automobile had not been invented, what would people use for basic transportation? |
| unless | condition | I won’t go unless you do. |
| when | time | Your heart rate increases when you exercise. |
| while | time | Some people like to listen to music while they are studying. |
| as | time | One train was arriving as another was departing. |
| since | time | We haven’t seen Professor Hill since she returned from her trip. |
| until | time | Don’t put off going to the dentist until you have a problem. |
| once | time | Once the dean arrives, the meeting can begin. |
| before | time | Before he left the country, he bought some traveler’s checks. |
| after | time | She will give a short speech after she is presented with the award. |
In Structure items, any part of a full adverb clause–the marker, the subject, the verb, and so on–can be missing from the stem.
Words that end with -ever are sometimes used as adverb clause markers. (In some sentences, these words are actually noun-clause markers, but they are seldom used that way in Structure items.)
The three -ever words that you are likely to see in the Structure Section are given in the chart below:
| Adjective Clause Marker with -ever | Meaning | Example |
| wherever | any place that . . . | Put that box wherever you can find room for it. |
| whenever | any time that . . . | They stay at that hotel whenever they’re in Boston. |
| however | any way that . . . | However you solve the problem, you’ll get the same answer. |
When the subject of the main clause and the subject of the adverb clause are the same person or thing, the adverb clause can be reduced (shortened). Reduced adverb clauses do not contain a main verb or a subject. They consist of a marker and a participle (either a present or a past participle) or a marker and an adjective.
When astronauts are orbiting the earth, they don’t feel the force of gravity.
(full adverb clause)
When orbiting the earth, astronauts don’t feel the force of gravity.
(reduced clause with present participle)
Although it had been damaged, the machine was still operational.
(full adverb clause)
Although damaged, the machine was still operational.
(reduced clause with a past participle)
Although he was nervous, he gave a wonderful speech.
(full adverb clause)
Although nervous, he gave a wonderful speech.
(reduced clause with an adjective)
You will most often see reduced adverb clauses with the markers although, while, if, when, before, after, and until. Reduced adverb clauses are NEVER used after because.
There are also certain prepositions that have essentially the same meaning as adverb-clause markers but are used before noun phrases or pronouns, not with clauses.
| Preposition | Related Marker | Example |
| because of | because/since | He chose that university because of its fine reputation. |
| due to | because/since | The accident was due to mechanical failure. |
| on account of | because/since | Visibility is poor today on account of air pollution. |
| in spite of | although/even though | He enjoys motorcycle riding in spite of the danger. |
| despite | although/even though | Despite its loss, the team is still in first place. |
| during | when/while | Her father lived in England during the war. |
In structure items where the correct answer is an adverb-clause marker, one of these words often appears as a distractor.
∇ Sample Item
No one knows what color dinosaurs were ________________ no sample of their skin has survived.
(A) because of
(B) because that
(C) it is because
(D) because
Choice (A) is incorrect; because of can only be used before nouns or pronouns. In choice (B), that is unnecessary. In (C), the phrase it is is used unnecessarily. Therefore, the answer is (D).
______________ rises to the surface of the earth, a volcano is formed.
(A) Liquid magma
(B) Whenever liquid magma
(C) Liquid magma, which
(D) That liquid magma
Choice (A) creates two clauses, but there is no connecting word to join them. (C) creates a sentence with a main clause and an adjective clause, but the main clause has two subjects (liquid magma and a volcano). (D) creates a noun clause. In a correct sentence, when a noun clause begins a sentence, the clause itself is the subject of the verb in the main clause, but this sentence already has a subject (volcano). Therefore, the correct answer is (B).
______________ invisible to the unaided eye, ultraviolet light can be detected in a number of ways.
(A) Although is
(B) Despite
(C) Even though it
(D) Although
The best answer (D) completes a reduced adverb clause. In choice (A), the adverb clause lacks a subject and is not a correct reduction because it contains a verb. In choice (B), despite cannot be used with an adjective (only with a noun phrase or pronoun). (C) does not supply a verb for the adverb clause and is not a correct reduction because it contains a subject.
Because ______________, alabaster can be easily carved.
(A) is soft
(B) softness
(C) of its softness
(D) of soft
Choice (A) lacks a subject in the adverb clause. Choice (B), a noun, could only be used with because of. In (D), because of is followed by an adjective; to be correct, it must be followed by a noun phrase or pronoun. Therefore, the correct answer is (C).