英语中，do，does，did的使用很容易让部分同学迷惑。现在，我来总结一下区分它们的方法。
首先我们要知道，动词do是原形，did是do的过去式，does是do的第三人称单数。他们的区别在于：
1、实义动词的区别，也就是当do,did, does是做，*意思，在句子中做谓语时，要分清时态，一般过去式的句子里，用did,一般现在时的句子用do或者does.
例如：
I did lots of work yesterday.(一般过去式）
we often do morning erercises on the playground.（一般现在时，主语为复数） Amy sometimes does housework at home.（一般现在时，主语为单数）
2.助动词的区别。这三个词，还可以作为助动词，来帮助构成疑问句和否定句。用对它们，还是要区分时态。did 用于一般过去时态，而do和does还是用于一般现在时态。
例如：疑问句：
Did you play football yesterday? Yes, I did.
Do you like fish? No,I don't. I like meat.
Does Sam go to school on foot?No, he doesn't.
否定句：
They didn't go shopping last Sunday.
we don't have classes on Saturday.
Grangpa doesn't like fish.
