根据所给中文或单词写出正确的形式：

1. He _________ (重) about four kilograms when he was born.

2. He didn't pass the exam because he was too _________ (认真的).

3. He is very young, so he can't look after _________ (自己).

4. The doctor saved many people's _________ (生命).

5. Do you know that he is fond of _________ (收集) stamps?

6. There are lots of _________ (老鼠) in the old man's house.

7. Sandy's sister _________ (刷) her cat's fur once a day.

8. He wants to be a _________ (科学家) when he grows up.

9. I wanted to see the rainbow after the rain. But it didn't _________ (出现).

10. When I woke up at six, I heard somebody _________ (敲) on my door.

11. It's _________ (危险的) for you to cross the road when the lights are red.

12. I look forward to _________ (own) a computer.

13. ________ Julie ________ (feed) her pet last night? Yes.

14. Shall we go _________ (row) tomorrow? A good idea.

15. Mr. Wang _________ (find) a job in a big city two years ago.