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1.  Our exercises are corrected at home by the teacher.

2.  Ali’s mother was worried by his absence.

3.  Several new schools are being built in our town.

4.  Great progress has been made in industry, science and medicine.

5. A lion was killed by Sam last week.

6.  Your report must be handed in before the end of this month.

7.  The job had just been finished when the factory closed.

8.  That box hasn’t been opened for the past hundred years.

9. Are these letters going to be mailed soon?

10. The report shouldn’t have been finished yesterday.

11. Researches on SIDA began to be carried out by scientists two years ago.

1) their exerxies are corrected by teacher.

2)His mother had worried by Ali's absense.

3)several new schools was building in their town.

4)industry had made great progress, science and medicine.

5)A lion had killed last week

6)Your report had to hand before the end of this month

7)mk chưa bt làm 😀

8)That box had opend for the past hundred years

9)These letters is going to mailed soon ?

10)The report should had finish yesterdat .

11)The researches had begun to carry out on SIBA two yeaes ago .