1.  Tom (see)                   this film before 2.  I already (finish)                  my exercise. 3.  How long they (live)                  here? They (live)                   here since 1990. 4.  My father (just wash)                  his car. 5.  The students (discuss)                  the question recently. 6.  Mary (never, be)                   to Hanoi. 7.  We (know)                  each other for 5 years. 8.  So far we (learn)                  five lessons. 9.  We (be)                  pen pals for a long time. 10.  They (not stay)                  here since last week. 11.  Bob (see)                  this movie before. 12.  Sandra (lend)                  her brother $ 200 so far. 13.  Rashid (just pass)                  his driving test. 14.  Karen (study)                  Italian for three years now and is still studying. 15.  The teacher (already, tell)                   to be quiet.

Để giải các câu hỏi trên, bạn cần điền dạng đúng của động từ trong ngoặc vào chỗ trống.

1. Tom has seen this film before.
2. I already finished my exercise.
3. How long have they been living here? They have lived here since 1990.
4. My father has just washed his car.
5. The students have discussed the question recently.
6. Mary has never been to Hanoi.
7. We have known each other for 5 years.
8. So far we have learned five lessons.
9. We have been pen pals for a long time.
10. They haven't stayed here since last week.
11. Bob has seen this movie before.
12. Sandra has lent her brother $200 so far.
13. Rashid has just passed his driving test.
14. Karen has studied Italian for three years now and is still studying.
15. The teacher has already told us to be quiet.

3. How long have they been living here? They have been living here since 1990.

2. I have already finished my exercise.

1. Tom has seen this film before.

Phương pháp giải:

1. Để tìm các số tròn chục có hai chữ số, chúng ta chỉ cần liệt kê từ 10 đến 90 (10, 20, 30, 40, 50, 60, 70, 80, 90).
2. Để tìm số lớn nhất có hai chữ số, chúng ta có thể thấy rằng số lớn nhất có hai chữ số là 99.

Câu trả lời:
1. Các số tròn chục có hai chữ số là: 10, 20, 30, 40, 50, 60, 70, 80, 90.
2. Số lớn nhất có hai chữ số là 99.