问题补充：
---I don’t know . Can you help me? ---I think you should calm down and read texts.
A. how to do
B. what to do it
C. what to do
D. when to do
答案：
A. how to do
B. what to do it
(答案→)C. what to do
D. when to do
解析：句意：我不知道该做什么。你能帮助我们吗？我认为你应该冷静下来，读一下说明。疑问词+to do的结构。如何去做：how to do it .做什么：what to do何时去做：when to do .
