光纤材料中的杂质大致可分为两类，即（）与（）。

同义句转换

1. Children can't wait to open the presents.

Children are _____ _____ _____ _____ the presents.

2. I have a scarf. Its colour is yellow.

I have a scarf _____ _____.

3. I can't afford this pair of glasses. It's kind of expensive.

I can't afford this pair of glasses. It's _____ _____ expensive.

4. I don't know how I should do it.

I don't know _____ _____ do it.

5. People that have no hobbies are dull.

People _____ _____ are not dull.