概述
do、does、did 和 done 是英语中非常重要的动词形式，它们源自动词 do，在不同语境下承担助动词或实义动词的功能。
1. do
用于一般现在时，主语为 I / you / we / they 或复数名词时：
- Do you like coffee?
- We do our homework every day.
2. does
用于一般现在时，主语为 he / she / it 或单数名词时：
- Does she play the piano?
- He does his best.
3. did
用于一般过去时，所有人称通用：
- Did you go to school yesterday?
- She did not (didn't) finish her work.
4. done
是 do 的过去分词，常与助动词 have/has/had 连用，构成完成时态：
- I have done my homework.
- They had done everything before we arrived.
也可用于被动语态（较少见）：
- The work was done by him.
常见误区
- 不要混淆 did 和 done：前者用于一般过去时，后者必须搭配助动词使用。
- 疑问句和否定句中，do/does/did 本身无实义，仅起语法作用。