[英语课]

助动词do, does, did

英语中经常因为人称的关系，动词就有变化。这和中文不同。
最常听的如：你吃饭了吗？
            他吃饭了吗？    动词“吃饭”的形式都没有变化的。

而英语就有人称和数的变化。
助动词do, does, did 常用于疑问和否定句，当然也可用于动词原形前面作为强调。Do, does 的时态为“一般现在时”，did 用于“一般过去时”。
1. DO 用于第一、二人称 you 和 复数。
  eg.  Do you like football？Yes, I do.
          They don't  (do not) like basketball.
2. DOES 用于第三人称单数 (he, it, she, etc.)
    eg. She doesn't (does not) have a brother.
         Does it take a long time?
          The boy doesn't go to school yet.
3. DID 用在“一般过去时”的句子中，没有人称的变化。
   Did you / she/ he / they see the movie？
   We/ He/ They didn't have dinner yet.
4. 用于强调。
I do believe you. 我肯定相信你。
They did visit there before. 他们确实去过那里。

[家教老师]

do, does, did 的否定形式只需要在后面加上not 就可。
如下：
             

don't = do not
         
           doesn't = does not
           
                                         didn't = did not

 eg: I don't know what you mean.
       She doesn't like dancing.
       They didn't go to the movie last night.