Question

Complete the sentence with an auxiliary verb:
I wasn’t tired but my friends______________
(A) do
(B) were
(C) could
(D) should

Answer 1

Hint:An auxiliary verb (abbreviated aux) is a verb which gives the clause in which it appears a functional or grammatical sense in order to convey tense, aspect, modality, voice, emphasis, etc. Usually, auxiliary verbs follow a primary verb. In the phrase I have finished my lunch, an example is the verb have. Auxiliary (or Helping) verbs are used to demonstrate the tense of the verb or to form a negative or question along with a main verb. The most common auxiliary verbs are have, be, and do.

Complete answer:
The verb 'was' refers to the tense of the past. Two acts that are parallel in meaning are mentioned in the given sentence. I wasn't exhausted, but my friends were exhausted. 'But' compares these two acts with 'I was not tired,' but 'my friends were tired.' (Also,' but my friends are an elliptical expression, where the verb 'tired' is absent. Whether it has been discussed before, a word may be omitted or inferred. The word 'tired' has previously been discussed and is therefore omitted.)
Option A: 'Do' applies to an action. But the verb "tired" is not an action but a state of being. It is also not compatible with the former part of the 'was tired' statement.

Option B: ‘Were’s the plural 'was' form. The subject and verb must agree in number with each other. So when the subject 'I' is singular, the verb is singular 'was' and the verb 'were' is also plural when the subject 'friends' is plural. A full meaningful sentence is formed by this verb, and thus option B is right.

Choice C: 'Could' refers to an option. Any of these moods (possibility or obligation) are not conveyed by the sentence.

Option D: 'Shall' refers to a proposal or task. Any of these moods (possibility or obligation) are not conveyed by the sentence. Options A, C and D are also incorrect.

Hence the correct answer is option ‘B’.

Note: Study the rules of tenses properly to answer these types of questions. Focus on which helping verb is used in what conditions. Overall first you need to have a good look at tenses before giving a try to this type of a question.