1. My grandparents walk _____ twenty minutes a day. for since 2. How long is it _____ you visited your grandparents? for since 3. We have been dating _____ a long time. for since 4. That lady has been waiting for the bus _____ noon. for since 5. I studied for this test _____ three days straight. for since 6. My family has lived here _____ last March. for since 7. She has worked there _____ she finished college. for since 8. I have been calling you _____ half-an-hour. for since 9. Lisa and Jill have been at the library _____ a long time. for since 10. My teacher has been sick _____ last Monday. for since

1. My grandparents walk for twenty minutes a day.

2. How long is it since you visited your grandparents?

3. We have been dating for a long time.

4. That lady has been waiting for the bus since noon.

5. I studied for this test for three days straight.

6. My family has lived here since last March.

7. She has worked there since she finished college.

8. I have been calling you for half-an-hour.

9. Lisa and Jill have been at the library for a long time.

10. My teacher has been sick since last Monday.

GT:

+ ''Since'' được dùng nhiều trong các thì hiện tại hoàn thành. Cụ thể hơn để chỉ mốc thời gian diễn ra sự việc hoặc chỉ mốc thời gian hành động đó xảy ra

+ ''For'' được dùng để chỉ 1 khoảng thời gian mà sự việc hay hành động diễn ra, kéo dài trong suốt khoảng thời gian đó. Trái với ''since'', ''for'' dùng được với tất cả các thì.