Question

Fill in the blank with the correct auxiliary verb from the choices given:
He _____ be very rich those days.
A) Used to
B) Was
C) Did
D) Can

Answer 1

Hint: Auxiliary verb: A verb used in forming the tenses, moods and voices of other verbs. There are two types of auxiliary verbs: (1) Primary Auxiliary verbs are be, do and have. (2) Modal Auxiliary are can, could, may, might, must, shall, should, will, and would.

Complete answer: The word “those days” in the sentence indicates that the verb is in the past tense.
Option A) Used to- is a correct answer. The auxiliary used (to) expresses an action. The phrase, 'used to + verb' indicates the verb in the past tense. The phrase, 'Used to be' means the same as 'was'. Hence, this auxiliary is appropriate to denote the action of ''being rich' in the past (indicated by 'those days').
Option B) Was – is an incorrect option. The word, 'was' is the past tense form of the verb. It cannot be used along with the word 'be' in the sentence. The phrase, 'was be' is grammatically incorrect.
Option C) Did is an incorrect answer. The auxiliary, 'did' is the past tense form of 'do' and is used for emphasising the verb which follows. However, 'did' cannot be used to emphasis the verb 'be'. The phrase, 'did be' is grammatically incorrect.
Option D) Can is an incorrect answer. The auxiliary, 'can' expresses ability or capability or permission. The phrase, 'can + verb' indicates permission given to do an action in future. It cannot be used to express a verb in the past tense.

 Note: In such type of question it is very important to understand the tenses and their uses to get the best fit in the sentence.