It's a waste of time doing sth.

It's a waste of time doing sth. 有it is a waste of time doing sth 这种用法吗? It's a waste of time exactly! it is a waste of time doing接SB怎么接 it is no wonder to do sth接 it is a waste of time doing还是to do a waste of time后面是加 doing sth还是to do sth I --- --- shopping.It's a waste of time. It's a waste of time这个句型,急, it's a waste of time your talking to him It is a waste of time doing this这里为什么用doing而不用do?为什么? waste time to do sth还是waste time doing sth? 请问,It is a waste of time 后该用to do 还是 doing