Số học sinh khá là:

\(\dfrac{45}{5}.3=27\left(học.sinh\right)\)

Số học sinh giỏi là:

\(\dfrac{27}{3}=9\left(học.sinh\right)\)

Số học sinh trung bình là:

\(45-27-9=9\left(học.sinh\right)\)

1 If people did more exercise, there would be less heart disease.

2 Children would have better teeth if they didn't eat too many sweets.

3 If the air were fresh, we would feel healthy.

4 If today were Sunday, I could take you to the circus.

5 We would have visited the museum if we had had enough time.

6 If my English were better, I would feel more confident at interviews.

7 If we don't protect wildlife now, there will be nothing left for our future generations.

8 If we had enough money, we would be able to buy that house.

9 If I hadn't gotten stuck in a traffic jam, I wouldn't have missed the train.

10 If he were more intelligent, he would be able to answer this question.

11 If Mary had come, we wouldn't have cancelled the meeting.

12 If Mr Minh had more time, he would read more English books.

13 If you could speak English, we would be able to offer you a job.

14 If my mother were here now, she would be able to help me.