The first function of 'DO' is as an auxiliary verb, to form questions and negative statements. But, like the verbs BE and HAVE, the verb DO can also be used as a main verb.
• I do
• You do
• He, She, It does
• You do
• We do
• They do
For example:- She does her homework.
- They do it all the time.
- The car does this when it is cold.
- Machines do the difficlult work.To express the question form in the simple present, we use the following structure:
• Do/Does +Subject + verb + rest of the sentence.
For example:
- Do you eat meat?
- Does she come?
- Do you understand now?