This is a very important class on ' It is time | It is high time | It is about time |
' High time ' is an idiom and it has a fixed structure,
It is high time + Subject + Past Subjunctive
It is about time + Subject + Past Subjunctive
It is time + Subject + Past Subjunctive
But,
It is high time to + verb1 (Incorrect)
It is about time to + verb1(Incorrect)
All these structures are possible in ' It is time'
It is time to + do (sth)
It is time for (sb) to do (sth)
It is time (sb) did (sth)
High time/About time always sits with or goes with Past Subjunctive, never with Infinitive.