Question

what is bare infinitive? explain with the help of examples

Answer 1

The bare infinitive is used as the main verb after the dummy auxiliary verb do, or most modal auxiliary verbs (such as will, can, or should..)
Examples:
I do know him 
I do like you.
I can do it .

Answer 2

 the infinitive without to, as used with modal auxiliary verbs.

 In the sentence I must go to the store now,the verb go is a bare infinitive.

for details 

see attached pic