It's up to you.

由你决定。

I'm afraid I can't.

恐怕我不行。

Don't bury your head in the sand.

不要逃避现实。

He realized that he was heading in the wrong direction.

他意识到走错了方向。

She counted on us to help her.

她指望我们帮助她。

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。