Fill in the blank with the most appropriate word.

The doctor often made his patients ______ for long.

wait

The doctor often made his patients wait for long.

Explanation:

• Waited: This form is the past tense of "wait," but it doesn't fit the context because the sentence is discussing a habitual action (present tense).

• Waiting: This form is the present participle of "wait," but it's not the best fit here because the sentence requires the simple form of the verb.

• To wait: This phrase isn't suitable in this context. The sentence structure should use the simple form of the verb "wait."

• Wait: This is the correct choice. The sentence requires the simple form of the verb "wait" to express the doctor's habit of making patients wait for a long time.