第1个回答 2013-07-08
do是原形,does是第三人称单数(he, she, it)形式;did是过去式:
I/we/you/they do homework in the morning.
He/She/Xiao Ming does homework in ....
We/THey/You/I/She/He did homework yesterday.
do 还可以是助动词,即帮助主要动词构成否定、疑问和时态等。
I don't know.
He doesn't know.
Did they kow ...?
You didn't know ... do用于关于第一,二人称或复数的陈述句主语后和疑问句的句首。
does用于第三人称的陈述句主语后和疑问句句首
did用于过去式(无人称限制)的陈述句主语后和疑问句句首
didn't用于过去式的否定句中的主语后,也用于反意疑问句 希望能帮得到你,谢谢!