We think that it's unuseful to explain the matter to him.

我们认为向他解释这件事是没用的。

If he continues to buy unuseful things, he is in danger to spend all his money.

假如他继续买些无用的东西，就会把钱全部花掉。

In this word no man is unuseful . in contrary, everyone is the best . so we have to respect everyone! even a beggar!

不要嘲笑任何一个你看不起的人！相反，还要尊重别人看不起的人！我想这就是人际关系。

But conventional methods are unuseful as the tiny displacement is hard to detect under cryogenic environment where superconductor works.

由于超导体需运行在极低温环境，运用常规方法难以对超导体的微小位移进行测量。