An adverb clause is a dependent clause that modifies a verb, adjective, or adverb in the main clause. It is introduced by a subordinating conjunction (because, although, when, if, since, as, after, before, until…). In diagrams, it is placed below the main clause with the conjunction on a broken diagonal connecting the two verb lines.
Diagramming the Adverb Clause
“Marty wanted to climb Mt. Everest because it is the world's highest mountain.”
Step 101 — adverb clause 'because it is the world's highest mountain' modifies 'wanted'
Concessive Clauses (although, even though)
“Although school had been dismissed early, we got home late.”
Step 102 — concessive adverb clause introduced by 'Although'
Comparative Clauses (as…as, than)
Comparative sentences with as…as (equal) or than (unequal) contain an elliptical dependent clause — some words are omitted because they repeat the main clause. The omitted words are represented by x in the diagram.
“This store is as large as that one.”
Step 106 — equal comparison; elliptical clause 'as that one [is large]'