Question

It's a waste of time这个句型,高手请进,急,谢谢

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?

Answer 1

分析一下句子结构你就明白了：It是形式主语，并非真正的主语。to do sth 或 doing sth 才是真正的主语。所以两者均可。It's a waste of time＋to do sth / doing sth 可以改为这种比较易懂的形式：
to do sth /doing sth is a waste of time 例如：
It's a waste of time watching TV=Watching TV is a waste of time.=It's a waste of time to watch TV.=To watch TV is a waste of time .不知你明白了吗？

Answer 2

也就是talking
to
him这个动作的执行者。也就是动名词前面加上了自己的主语，指代实际的主语动名词短语talking
to
him。
it是形式主语.和他说话是浪费时间it
is
a
waste
of
time
talking
to
him;sb(宾格)
+
doing
sth”叫做动名词的复合结构。动名词的复合结构和动名词作的成分是一样的.
your是动名词短语的逻辑主语;s/。
“one'

Answer 3

后面接doing，固定搭配

Answer 4

加doing sth
这个比较特殊

Answer 5

It + be + 名词词组+doing sth 固定搭配
It + be + no + 名词+ doing sth