An adverb clause is a group of words that is used to change or qualify the meaning of an adjective,verb, a clause, another adverb, or any other type of word or phrase with the exception of determiners and adjectives that directly modify nouns.
Adverb clauses always meet three requirements:
As you read the following adverb clause examples, you'll notice how these useful phrases modify other words and phrases by providing interesting information about the place, time, manner, certainty, frequency, or other circumstances of denoted by the verbs or verb phrases in the sentences. While adverb clauses are slightly more complicated than simple adverbs, they are worth learning about.
The adverb clauses in these examples are italicized for easy identification.