They __________ this research for years. A. have done ...

[ Tenses ]

They __________ this research for years.

A. have done

B. have been doing

C. were doing

Select your answer:

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Other quiz:

Passive Voice › View

He delivered the letters.

A. The delivered the letters he

B. He the letters delivered..

C. The letters were delivered by him.

D. Were the delivereed the letters by him.

Grammar › View

Lina always _____________ with her friends
A. travelling
B. travel
C. travels
D. travelled