来自蔡志旻的问题
【Thestudentsareplayingfootballintheplayground.(改为否定句)】
Thestudentsareplayingfootballintheplayground.(改为否定句)


【Thestudentsareplayingfootballintheplayground.(改为否定句)】
Thestudentsareplayingfootballintheplayground.(改为否定句)
Thestudentsaren'tplayingfootballintheplayground.