1.They (clean)cleaned the beach one week ago.

2. They (collect)have collected hundreds of books so far.

3. I (collect)collected stamps when I was a child.

4.She (fly)have flown to Da Nang many times but last year she (go)went there by train.

5. Have You ever (see)seen a real lion? No, but I (see)saw a real elephant when we went to the zoo last month.

1. They cleaned the beach one week ago.

- dấu hiệu thì quá khứ đơn: one week ago

- S + V2/ed + O

2. They have collected hundreds of books so far.

- dấu hiệu thì hiện tại hoàn thành: so far

- S + V3/ed + O

3. I collected stamps when I was a child.

- dấu hiệu thì quá khứ đơn: I was a child

- S + V2/ed + O

4. She have flown to Da Nang many times but last year she went there by train.

- dấu hiệu thì hiện tại hoàn thành: many times

- S + V3/ed + O

...............................................................................................

- dấu hiệu thì quá khứ đơn: last year

- S + V2/ed + O

5. Have you ever seen a real lion? No, but I saw a real elephant when we went to the zoo last month.

- dấu hiệu thì hiện tại hoàn thành: ever

- S + V3/ed + O

..............................................................................................

- dấu hiệu thì quá khứ đơn: last month

- S + V2/ed + O