题目

Where do they come from?What do they usually do
Where do they come from?
What do they usually do
When do the children do their homewore?为什么 前面要加do

提问时间：2020-07-24

答案

因为这些都是特殊疑问句,然而,他们的原句没有be动词,就需要助动词do来变疑问句