Read and translate.小小翻译家。（将下列句子翻译成汉语）   

1. What’s their favourite colour?

2. I like to wear hats on my head.

3. They like fish and rice for breakfast.

4. They like to sing songs in the library. 

5. People always get mad at him.

一对渐开线直齿圆柱齿轮，只要压力角相等，就能做到正确啮合和传动平稳。