I envy you.

我羡慕你。

I'm all mixed up.

我全搞混了。

I think it's a reasonable price.

我觉得这是个合理的价钱。

The girls all went crazy over him.

姑娘们都为他神魂颠倒。

Nothing gives me more pleasure than learning English.

再也没有什么比学英语更让我高兴的事了。

Knowing what he is capable of, you have every right to be afraid.

既然你知道他的能力如何，你的担心是完全可以理解的。