1、作为实义动词/行为动词，跟其他动词一样，如study, play等，do和does都是“做”的意思，都是一般现在时，主语是第三人称单数用does，其余人称用do。

例句：We usually do our homework in the afternoon.He does his homework in the evening.2、作为助动词，也就是帮助主要动词构成否定和疑问等，没有意义，主语是第三人称单数用does，其余人称用do，后面的动词都用原形。例句：We don't like bananas. Do you like apples Does he like EnglishHe doesn't like swimming.