Question

Choose the most suitable option to replace the highlighted part of the sentence: It is high time you must change your habits.

• A. changed your habits
• B. must have changed your habits
• C. change your habit
• D. will change the habit

Answer 1

Answer:

A. changed your habits

The phrase "It is high time" (as well as "It is time" or "It is about time") is an idiomatic expression used to indicate that something should have been done already, and that it is late.

There is a strict and unique grammatical rule governing this phrase:

It is high time + Subject + Simple Past Tense ($V_2$ form of the verb)

1. Why the Simple Past is used: Even though the sentence implies that the person needs to change their habits right now or in the future, English grammar requires the Simple Past tense after this specific phrase. This is called the unreal past or subjunctive mood, used because the action has not actually happened yet but should have.

2. Applying the rule: The subject is "you". The verb is "change". Following the rule, "change" must be converted into its simple past form, which is "changed". The helping or modal verb "must" should be removed completely.