你怕什么英语怎么说....谢谢。

of是不能省略的
When will you have a rest?

不可以省略 是固定搭配

When will have a rest?

是的‘不能省略的‘

When will you want to have a rest?

what do you fear?
when will you have rest?

What are you scared of?
你害怕什么？
When will you have a break?
你什么时候休息一下？
比较口语化.