a waste of time后面是加 doing sth还是to do sth

a waste of time后面是加 doing sth还是to do sth she thinks it a waste of time如何理解,为什么it后面不加is a waste of time a waste of time后加TO DO还是DOING waste修饰名词要加of吗 例如a waste of time 短语a waste of time 后加的是 to do还是 doing? It's a waste of time这个句型,急,It's a waste of time 后面加to do sth还是doing sth?到底哪个正确呢?还是两个都有? be taken a waste of time 是固定用法吗? 是It is a waste of time to play computer games 还是Playing computer games is a waste of time “Bai Feili”means（ ） A.a waste of time B.waste of time C.a waste of a time D.waste of a time 答题详细点. a waste of time 怎么造句? It is only a waste of time it was a waste of time and a waste of time 咋个造句 用“a waste of time”造句. 怎么用a waste of time造句 It's a waste of time exactly! A waste of time and effort