The researchers ....................... hard to develop a perfect new model ... | GrammarQuiz.net

Topics: TOEIC Grammar and Vocabulary Review

The researchers ………………….. hard to develop a perfect new model over the last two years.

A. work

B. worked

C. are working

D. have been working

Select your answer:

Random Topics:

Phrasal verbs and Prepositional Phrases Grammar, Literature, and Vocabulary Reported - Gerund Adverb Clauses Modal Verbs & Perfect Infinitive -ed/-ing Adjectives Present Simple Progressive Noun Clauses with THAT Simple Compound and Complex Sentences Passivisation

Other quiz:

Grammar › View

We must _________ the animals.

A. loves

B. loving

C. love

Grammar › View

Choose the English equivalent of the word natychmiast.

A. immediately

B. just now

C. these days

➤