Câu hỏi: ............. the experiment three timesnow with different results each time!

A. We’ve done

B. We did

C. We’ve been doing

Câu 1: While we’re working on the project ourboss ................ on a beach in Greece!

A. will sit 

B. will have sat

C. will be sitting

Câu 2: I don’t know whether to accept the joboffer. It’s .................

A. a difficult decision

B. the difficult decision

C. difficult decision

Câu 3: I..................want to be a practising doctor but now I’m more interested in research.

A. was used to

B. used tocorrect

C. would

Câu 4: They.......................personal computers when my father was a student.

A. hadn’t

B. didn’t havecorrect

C. weren’t having

Câu 5: The teacher..................... us how to do the experiment when the fire bell rang.

A. showed

B. shown

C. was showing

Câu 6: She..................some friends to her house for a party.

A. decided

B. agreed

C. invited