It is +adj doing 什么时候用?It is +adj to do什么时候用?

It is +adj doing 什么时候用?It is +adj to do什么时候用?

It is + no use, no good (fun, a great pleasure, a waste of time, a bore...)等名词+doing sth.
It is no use crying.哭没有用.It is no good objecting.反对也没有用.
It is a great fun playing football．打篮球很有趣.
It is a waste of time trying to explain．设法解释是浪费时间.
It is + useless (nice, good,interesting, expensive等形容词)+ doing sth．
It is useless speaking.光说没用.
It is nice seeing you again．真高兴又遇到了你.
It is good playing chess after supper．晚饭后弈棋挺好.
It is expensive running this car．开这种小车是浪费.