i don't know___with this problem it is too hard 为什么是what to do 不是how to do?

i don't know___with this problem it is too hard 为什么是what to do 不是how to do?
i don't know___with this problem it is too hard 为什么是what to do 不是how to do?

i don't know___with this problem it is too hard 为什么是what to do 不是how to do?
how只能与deal with搭配,侧重方式
what 与do with搭配,侧重所作的事