Math is beyond me.

我对数学无能为力。

That was a lousy movie.

那电影糟透了！

I don't seem to have any luck today.

我今天运气不好。

He is a big figure in the business world.

他在商界是一位很有威望的人。

I don't know how to work the machine.

我不懂得怎样使这部机器运转。

I've had no time to prepare for this meeting, so I'll have to play it by ear.

我没有时间来准备这次会议，所以只好有什么说什么。