意思不同:
1、do:做,干,办(某事)。
2、did:做,行动,表现。
词性不同:
1、do:do是动词原形。
2、did:did是do的过去式。
1、What time did you get back last night?
你昨晚什么时候回家的?
2、I could do it now, if you like.
如果你愿意的话,我现在就可以做这事。
3、What in the world did they think they were doing?
他们到底认为自己在做什么?
4、One major problem did present itself, though.
不过,确实出现了一个重大问题。
5、Do it now please ─ not in three hours' time.
请现在就干,而不是三个小时之后。