按要求改写句子。

1. Sometimes I watch TV. Sometimes I read magazines. (用or把两句连成一句)

2. What do you usually do at the weekends? (写出同义句)

3. He likes playing on the swings. (改为否定句)

4. Nancy often goes to the park at the weekends. (对画线部分提问)

5. An insect is my good friend. (改为复数句子)

低流量麻醉的优点不包括（）。

A.减少麻醉药用量

B.减少手术室污染

C.保持环路内湿度

D.保持环路内温度

E.初学者容易掌握