do用在第一和第二人称以及第三人称复数前面,而DOES用在单数第三人称前面.疑问句和否定句中DO和DOES要放在实意动词前
DO you like this?yes,I do/no,I DON'T
Does she have a nice bag?YES,SHE DOES/ NO,SHE DOESN'T