用所给词的正确形式填空。    

1. The students ____ (talk) to each other in the classroom now.

2. How ____ (do) Liu Ming and Liu Ping spend their weekends?

3. I'd like ____ (catch) some ____ (dragonfly) in the park.

4. School ____ (be) over. I can go home now.

5. Ben usually ____ (go). ____ (climb) on Saturdays.

粉尘粒径的分布函数常用的有（）、对数正态分布和罗辛-拉姆勒（R-R）分布函数。