Question

Choose a suitable option to fill in the blank with a modal that denotes past habit:

Dennis gave up smoking two years ago. He _____ smoke 40 cigarettes a day.

• A. has to
• B. have to
• C. used to
• D. had to

Answer 1

The correct option is C used to

A verb that functions to some extent like modal verbs called semi- modal verb and Modal Verbs show us the attitude of the speaker to what is being said or done. The term "modal" means expressing mood and mood is a way to express the attitude of the speaker.

Option C is the correct answer because it denotes past habit.

Whereas Option A, B and D express extreme obligation.