They are good at swim.They are good at swimming.这两个表达方式都对吗?请说明.

问题描述:

They are good at swim.They are good at swimming.这两个表达方式都对吗?请说明.
书上说good at 后面可跟名词、动名词,是不是这两种表达方式都是正确的.

They are good at swimming 才对
swimming 名词,解作游泳活动
swim 作名词,解作游泳使用时间