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.