I don't know【 】next.为什么就一定要是what to do 不能是how to do

问题描述:

I don't know【 】next.为什么就一定要是what to do 不能是how to do

what to do 表示:做什么 已经完整了
how to do 表示:怎么做.后面还要有内容的
所以这里只能选what to do
可以说:
I don't know【what to do 】next
I don't know【how to do the plane 】next