a. What is an adverb clause?

(relevant: VI-E)
An adverb clause usually expresses one of the following relationships to the main clause.
a. cause and effect
b. contrast or comparison
c. time
d. condition

Improve your writing: Adverb Clauses
source: AlexESLvid        2011年6月17日
quiz at http://www.engvid.com/adverb-clauses/...

What is an adverb clause?
LearnAmericanEnglishOnline  2009-04-13

Adverb clauses
source: MrGrammarMan123   2012-03-27

Adverb Clause
source: Iken Edu       2012年2月24日

The Adverbial Clause
source: iewtv      2008年10月8日

Adverbial Clauses: Time Clauses
source: EnglishTeacherMarc      2017年10月8日
Adverbial Clauses: CONCESSIVE             2018年2月18日