did（一般过去时）,have（现在完成时）,do（一般现在时）,does（一般现在时,主语为三单）,has（现在完成时,主语为三单）,had (过去完成时)这些词都可以是助动词,用于不同时态的否定句和疑问句
另外,这些词也可以是实义动词
做：do（一般现在时)I do my homework every day.
does（一般现在时,主语为三单）My mother does housework every day.
did（一般过去时）They did their best yesterday.
有：have（一般现在时)I have a book.
has（一般现在时,主语为三单)She has a pen.
had (一般过去时)They had dinner at 7 yesterday.