[ Verb Tenses ]
_____ with Dr. Browne since your project in 2018?
A. Do you collaborate
B. Had you collaborated
C. Have you collaborated
D. Are you collaborating

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Verbs and PrepositionsConjunctive AdverbsComplex Sentences with Adverb ClausesConjunctions, Interjections and DeterminersGrammar, adverbs of frequency placementPresent Progressive (Future)Verb FormComparatives, Superlatives & EquativesBasic GrammarTOEIC Grammar and Vocabulary ReviewOther quiz:
Present Perfect vs Past Simple › ViewI haven’t seen my parents _____ last Christmas.
A. already
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C. for
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Prepositions › View
The children walked __ the park to get home quickly.
A. For
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C. By