根据首字母提示完成填空。

1. Surfing is enjoyed by people all over the W____.

2. Don't be afraid. I'll s____ you how to dance.

3. He p____ his English every day, so he gets good grades.

4. Don't w____ about your lessons. I will help you.

5. I really m____ the old days.

简述自动化驼峰溜放速度控制系统的结构。