1. I have been in this class for a month

2. I have known my teacher since September

3. Our professor has been sick for a week

4. They have lived in Canada since December

5. I have known Mrs Brown since 1999

6. Tom has worked at a fast-food restaurant for three weeks

III . Rewrite the sentences using since or for.

1. I was in this class a month ago, and I am in this class now.

=> I have been in this class since one month ago/ for one month(chọn cái nào tùy).

2. I knew my teacher in September, and I know her now.

=> I have known my teacher since September.

3. Our professor was sick a week ago, and he is still sick.

=> Our professor has sicked for a week .

4. They live in Canada. They moved there in December.

=> They have lived in Canada since December .

5. I know Mrs. Brown. I met her in 1999.

=> I have known Mrs.Brown since 1999 .

6. Tom works at a fast - food restaurant.He got the job three weeks ago.

=> Tom has worked at a fast-food restaurant since three weeks ago / for three weeks (chọn cái nào tùy).