3. have not find ( HTHT)

4.did.... go ( QKĐ)

8have built / haven't complete ( HTHT)

9.have eaten/ate( HTHT)

Đáp án+giải thích:

present perfect: S+have/has+vpII

past simple: (+)S+ved

                      (-)S+ didn't+V

                      (?) Did+S+V?

3. People (not find) have found the solution to reduce the graffiti at school yet.

yet=> dấu hiệu thì present prefect

4.  Did Nhi (go) go to the concert last weekend?

last weekend=> dấu hiệu thì past simple

8) They (build)have built this hospital for over one year but they (not complete) haven't completed it yet.

for over one year, yet=> dấu hiệu thì present prefect

9) I (eat) have eaten this kind of food many times. The last time I (eat) ate it was last Sunday.

many times=>dấu hiệu thì present prefect

The last time=>past simple

Chúc bạn học tốt ^_^