The subjunctive mood in the attributive/subject clause:
The sentence begins with the principal clause and it is as follows:
It is time…It is about time…It is high time…
The subordinate clause is introduced by the conjunction that (which can be omitted).
Only the past subjunctive is used because the attributive clause describes the noun and it cannot express priority.
E.g. It is high time we dealt with the problem.…
