about后面加什么

It's about this high.

大约有这么高。

There was much discussion about the reasons for the failure.

就失败的原因进行了大量的讨论。

The population is increasing at about 6% per year.

人口以每年约6%的速度增加。

It's only human nature to be worried about change.

对变革有忧虑不过是人之常情。

We estimated it would cost about  5 000.

我们估计要花费大约5000欧元。