A singular subject takes a singular verb.

For example:

Singular subjectSingular verbIlike ( plural verb)to eat ice-cream.Helikesto eat fried rice.Shesingssweetly.Itdoesnot swim.

When the subject is singular, the verb must be singular. The singular verb normally ends with an s.

A plural subject takes a plural verb.

For example:

Plural subjectPlural verbThe boysThe girlsplaybadminton everyevening.YouTheyWedonot cook well.

When the subject is plural, the verb must be plural. The plural verb normally does not end with an s.

I and You are singular subjects but the verb which agree with them must be plural verb.

THE VERB TO BE

SubjectPresent FormIamHeSheItisYouWeTheyare

THE VERB TO BE

SubjectPast FormIHeSheItwasYouWeTheywere

THE VERB TO HAVE

SubjectPresent FormIhaveHeSheIthasYouWeTheyhave

THE VERB TO HAVE

SubjectPast FormIHeSheIthadYouWeTheyhad

THE VERB TO DO

SubjectPresent FormIdoHeSheItdoesYouWeTheydo

THE VERB TO HAVE

SubjectPast FormIHeSheItdidYouWeTheydid