I know 'Did' is the past tense of 'Do' and if we want to ask question in present tense 'Do you come?' and in past tense it is 'Did you come?'. Why don't we use 'Did you came?' as came is the past tense of come?
The verb DO takes a bare infinitive. In English verb constructions only one verb can have tense. This is always the first verb. So if did is past tense, come cannot be. It cannot be present tense either. It must be in the plain form:
- *Did she came. (ungrammatical)
- *Did she comes. (ungrammatical)
- Did she come. (beautiful)