例如：I often do my homework in the evening .

　　當主語是He/She/It或者其他單數名詞時，動詞用does。

　　例如：

　　She often does  homework in the evening .

　　2.作助動詞，無實際意思。通常用于疑問句和否定句。

　　(1)用于一般疑問句。直接在句首加上do/does，注意大小寫和部分人稱及動詞的變化。

　　例如：

　　I like apples.

　　Do you like apples?

　　Yes, I do.  /No, I don't.

　　當主語是三人稱單數時，用does.

　　例如：She likes apples.

　　Does she like apples?

　　Yes, she does.  /No, she doesn't.

　　(2)用于否定句時，在句子中加上don't或者doesn't.

　　例如：I don't like apples.

　　She doesn't like apples.