Mark the letter A, B, C, or D to indicate the correct answer to each of the following questions.

Câu hỏi

This is the first time I __________ the experiment on plant breeding.

A. have done

B. do

C. would do

D. did

Đáp án
A. have done

Câu hỏi thuộc Bài tập:

E9- TĐ- Đề ôn số 4