Question

什么时候用to do什么时候用doing 都是非谓语动词 有什么区别吗？

Answer 1

to do 是动词不定式，用于一般时态下的陈述句，如：You have to do your job perfectly. 而 doing 有两种用法，一是动词 ing 形式，相当于给句子润色，如：Everyone doing their jobs pretty well in this company. 二是表述现在进行时态，如：Sorry ! I can't. I'm doing my paper work right now.

Answer 2

区别取决于谓语动词，有的动词带不定式，有的带动名词，需要记忆，但有些有规律。
1. 表示要去做某事，后面带不定式，比如want, decide等。I want to visit Tom. They decide to buy this dog.
2. 表示喜爱，接动名词，不如Tom likes playing football. She loves dancing.