. Which sentence uses the past perfect continuous? a) I had been waiting for an hour. b) I waited for an hour.
A. I will wait for an hour.
B. I was waiting for an hour.
C. I have been waiting for an hour.
D. I had been waiting for an hour.

Random Topics:
Modals VerbPreposition (at,in,on)1st and 2nd ConditionalsSubordinating ConjunctionTenses: Present simple, Past Simple, Future SimpleAdverbs of How Something is DonePhrase or Clauselike/do not likeGerund/ To Verb/ VerbGrammar : Must (Necessity)Other quiz:
Grammar › ViewLet’s leave early. We can’t risk _____ in heavy traffic during rush hour.
A. to hold up
B. to be held up
C. holding up
D. being held up
Conjunctions › View
Name the type of conjunction
BECAUSE
A. coordinate
B. correlative
C. subordinate
Vocabulary and Grammar › ViewWhich word means “to know how something works or what it means”?
A. grow
B. pattern
C. solution
D. understand
Tenses › View
Which one is the correct answer for: Do you think he can do it all alone?
A. He don’t think you can do it all alone.
B. He doesn’t think you can do it all alone.
C. I don’t think he can do it all alone.
D. Don’t you think he can do it all alone.