[ Modals ]
So far scientist have not ___ to successfully devise a mechanism
A. been able
B. need
C. must

Random Topics:
Narrative Tenses & ConditionalsVocab CheckingDemonstrative PronounGrammar RulesGerunds and InfitinitivesBe Going To vs. WillModal Verb Gerund or To InfinitivePresent ContinuousSpeculation with Modal VerbsFrequency AdverbsOther quiz:
Grammar › ViewWhat is the correct abbreviation for October?
A. Octo.
B. Oct.
C. Oct
D. Octob.
Indefinite Pronouns › View
______ bought me a drink yesterday.
A. Something
B. Everybody
C. Someone
D. Somewhere
