[ Modal Verbs ]
No one knows exactly who were the first Americans, but scientists exploring caves have found evidence that they _____ from Asia.
A. should have arrived
B. would have arrived
C. must have arrived
D. ought to have arrived
E. have arrived

Random Topics:
Linking VerbPhrasal VerbsModalAdjectives and DegreesPassive Voice, Question Tag, PrepositionsTenses StructureGerunds and InfinitivesTypes of PrepositionAuxiliary and Modal VerbsGrammar of Conjunctions and PrepotitionsOther quiz:
Grammar › ViewAnita has arrived in the United States two years ago.
A. True
B. False
Vocabulary › View
the action of moving or changing position
A. force
B. motion
C. gravity
D. distance
Tenses › ViewWhat I …………….. is that we …………….. to think seriously about a thorough reform in the legal system
A. have proposed / should have begun
B. had proposed / were beginning
C. am proposing / begin
D. was proposing / have begun
Vocabulary › View
I cant give up and let go my hard work in ___________.
A. drain
B. vain
