根据首字母填空。

1. Han Hong sings very well. She is a f______ singer.

2. The doctor is looking at my mouth, he is a d_______.

3. His father is always doing experiments. He is a s_______.

4. We are p______ of our country.

5. Lucy r______ a lot of support from her friends.

简述ONAN发电机制动电路的作用。