1、作实义动词，也叫形为动词。和普通的动词一样，有自己的实际意思，表示“做”。

例如：do 、homework, do exercises等。

当主语是I/We/You/They或者复数名词时，动词用do。

例如：I often do my homework in the evening .

当主语是He/She/It或者其他单数名词时，动词用does。

例如：

She often does homework in the evening .

2.作助动词，无实际意思。通常用于疑问句和否定句。

(1)用于一般疑问句。直接在句首加上do/does，注意大小写和部分人称及动词的变化。

例如：

I like apples.

Do you like apples?

Yes, I do. /No, I don't.

当主语是三人称单数时，用does.

例如：She likes apples.

Does she like apples?

Yes, she does. /No, she doesn't.

(2)用于否定句时，在句子中加上don't或者doesn't.

例如：I don't like apples.

She doesn't like apples.