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 they had to go, everybody ................. Nina and her mother for the party.

A. said

B. thanked

C. told

Câu 2: …………. the doctor at 2.00 thisafternoon so I can’t go to the lecture.

A. I’m seeing

B. I see.

C. I will see

Câu 3: The teacher ............... us how to do theexperiment when the fire bell rang.

A. showed 

B. shown

C. was showing

Câu 4: She................ well at school but that changed when she became friends with a different group of girls.

A. did

B. had done

C. had been doing

Câu 5: …………. i the doctor at 2.00 this afternoon so I can’t go to the lecture.

A. I’m seeingcorrect

B. I see

C. I will see

Câu 6: They.......................personal computers when my father was a student.

A. hadn’t

B. didn’t havecorrect

C. weren’t having