3. It was not until then that I came to know that the earth ________ around the sun.

A. moved       B. has moved      C. will move       D. moves

4. When all those present（到场者）________ he began his lecture.（重点题）

A. sit       B. set       C. seated       D. were seated

5. If I had had time, I would have written to you. But in fact I ________ not.

A. have      B. would have      C. had       D. had had