I am going to go swimming tomorrow.swim为什么加ing

呵呵,lz这是动名词.比如go shopping
最后,动名词在多个动词句型中出现,如下列的“go, come, get, set”等动词就常和动名词连用：
12. Noelle and her friends go swimming every week.
13. When do they usually go shopping?
14. Would you come skiing with the kids?
15. Isn't it time to get the plan going?
16. What sets them quarrelling from time to time?
此外,下列这些动词也常和动名词组成动词句型：
17. The boy admitted stealing the book.
18. Don't forget handing in your homework in due course.
19. Would you mind taking me to the bus stop?
20. Jason cannot bear being cruel to the weak.
21. Nancy said that she regretted doing such a thing.
22. You must continue trying until you succeed.
23. Many young people enjoy watching sports and games.
24. Can't you avoid walking on my garden?
25. We all hate cheating, don't we?
综上所述,动名词和带“-ing”的名词虽然形式相同,但是特色有异,语法功能也跟着有所不同了.
楼主请参考：
http://www.zaobao.com/bilingual/pages1/jiangyi020901.html