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: When I arrived the lecture................ soI didn’t find it easy to follow.

A. started

B. had startedcorrect

C. had been starting

Câu 2: I ........... want to be a practisingdoctor but now I’m more interested in research.

A. was used to 

B. used to 

C. would

Câu 3: She..................some friends to her house for a party.

A. decided

B. agreed

C. invited

Câu 4: My sister.................... economics andpolitics when she goes to university.

A. is going to study 

B. studies 

C. will study

Câu 5: I don’t know whether to accept the joboffer. It’s .................

A. a difficult decision

B. the difficult decision

C. difficult decision

Câu 6: When I arrived the lecture .............. so I didn’t find it easy to follow.

A. started

B. had started

C. had been starting