Adverb Clauses

Compare We left early with We left because the bridge closed. Early tells you when we left, and the clause tells you why. Both modify the verb left, so both do an adverb’s job. The second does it with a whole clause, which has its own subject (bridge) and verb (closed).

An adverb clause is also called an adverbial clause: the dependency label advcl is short for adverbial clause modifier. It begins with a subordinating conjunction. That word makes the clause dependent: it cannot stand alone as a sentence. The conjunction also tells you what the clause adds:

• time (when?): when, while, before, after, until, since
• reason (why?): because, since
• condition (under what condition?): if, unless
• contrast: although, while
• comparison: than (see What the clause modifies, below)

Since and while each have two meanings, so read the whole sentence. When is special: traditional grammar calls it a relative adverb. Its dashed line has a short solid piece at each end, and the dependency tree labels it advmod, not mark.

Both kinds of conjunction can join two clauses, but they give different diagrams and different labels in the exercises.

• A coordinating conjunction (and, but, or) joins two equal, independent clauses. Reed-Kellogg stacks their base lines and joins the two verbs with a dashed step-down. The tree labels the conjunction cc and the second verb conj, and Roles boxes two Main clauses. See Compound Sentences.
• A subordinating conjunction makes one clause depend on the other. The dependent clause hangs below, on a slanted dashed line from the word it modifies. The tree labels the conjunction mark and the clause’s verb advcl, and Roles boxes an Adverb clause.

An adverb clause usually modifies the main verb. It tells you when, why or under what condition the action happens. In Because the bridge closed, we took the ferry, the clause tells you why we took the ferry, so the dashed line starts at took.

An adverb clause can also modify an adjective or an adverb. Comparisons with than are the common case. In The lake was colder than it looked, the clause than it looked answers the question colder than what? It modifies the adjective colder, not the verb was.

A subordinating conjunction needs a clause after it, with its own subject and verb. Some prepositions have the same meaning but take a noun phrase instead, and Spanish speakers often mix up the pairs. Most items show an error (✗) and a correct version (✓).

• because + clause, because of + noun phrase. ✗ We cancelled the picnic because the rain. ✓ We cancelled the picnic because of the rain. ✓ We cancelled the picnic because it was raining.
• although + clause, despite + noun phrase. Spanish a pesar de que is although, and a pesar de is despite. ✗ Despite the traffic was heavy, Marta arrived on time. ✓ Although the traffic was heavy, Marta arrived on time. ✓ Despite the traffic, Marta arrived on time.
• while + clause, during + noun phrase (mientras, durante). ✗ Diego read during the baby slept. ✓ Diego read while the baby slept. ✓ Diego read during the flight.
• No will after when, until, before, after or if in an adverb clause. A present form already gives the future meaning. ✗ Santiago will call his mother when he will land. ✓ Santiago will call his mother when he lands. The Tense page compares this with Spanish cuando llegues.
• A comma after a clause that comes first. Because the bridge closed, we took the ferry. When the clause comes last, you usually need no comma: We took the ferry because the bridge closed.