1. 选用括号里动词的适当形式填空

knock on, hunt, feed, look after, be healthy, brush, worry about, do exercise, catch up, not be late

1. （1） He didn't study hard. So his parents often his lessons.
3. （2） If you are busy at work all day, you can keep goldfish. Because they are easy .
5. （3） Go and see who the door.
7. （4） If you want to be healthy, you need every day.
9. （5） He was late for school. The teacher told him again.
11. （6） Men like going on mountains.
13. （7） My grandfather spends a lot of time his pet every day.
15. （8） It's necessary to walk the dogs once a day if you want them .
17. （9） He was away from school for two months. I'm sure she will do her best.
19. （10） He is a neat boy He his teeth twice a day.