Question

Choose an appropriate option to fill in the blank:
Bill and Sue go away on holidays very often, so they _ _ _ _ _ _ be short of money.
A. couldn’t
B. can't
C. mustn’t
D. won't

Answer 1

Hint: The sentences that we read and study in grammar are made up of a few, specific elements that help in forming the basic meaning of the sentence. We have read and studied about the subject which is used to describe the nouns, pronouns, and noun phrases that occur before the verb in a sentence. It is the agent who causes the action. Then in line is the object which can be a noun, a noun phrase, or a pronoun. It is affected by the action of the verb. Then the ‘verbs’ come into play and show what is being done in the sentence. They are accompanied by auxiliary or helping verbs like can/cannot, will/won’t, shall/shan’t, must/mustn’t etc.

Complete step by step answer:
1. In order to find the word which will be the appropriate option to fill in the blank, we have to check each option one by one so that we can detect the correct option.
2. The word- couldn't is a contraction of the words ‘could not’. An example of its use in a sentence will be - “I was so excited that I couldn't sleep”. If we examine this sentence, we can see that the speaker was unable to sleep due to his/her excitement. Thus, this word refers to an inability in the past. If this word is inserted in the sentence given in the question, the meaning will not be understood clearly. Hence, this option is incorrect.
3. The word- can't is a contraction of the word ‘cannot’. For example, in the sentence - “I can’t do it. It's impossible”, we can see that the speaker is conveying the fact that he/she is not capable of doing an action that he/she thinks as something that is extremely difficult. Thus, this word refers to an impossibility in the current moment. If this word is inserted in the sentence given in the question, we can say that it will complete the meaning of the sentence and will make it sound comprehensive. Hence, this option is correct.
4. The word “mustn’t” is the abbreviation of ‘must not’. This refers to something that is strictly prohibited. If it is added in the sentence given in the question- “Bill and Sue go away on holidays very often, so they _ _ _ _ _ _ be short of money”, it will not make sense. This will be because Bill and Sue have not been forbidden to not have shortage of money. Thus, this option is wrong.
5. “Won’t” indicates the least possibility of an action. It is the abbreviated form of ‘will not’. This word is somehow similar to ‘must not’. Although the former is a bit ‘strict’, both convey the same meaning. ‘Won't’ can be used in a sentence like- “I won’t eat for a day” where it signifies the emotion of the speaker to not eat for a day. Whereas, ‘Mustn’t’ can be used in “You mustn’t eat that” where it signifies strict prohibition. Thus, the word “won’t” is not correct.

Therefore, the correct answer to this question is option B.

Note:
Sentences are formed by a few grammatical elements that bring out their basic meaning. These elements can be the subject, object, the verb and the helping verbs. If you notice the question sentence, you will find the part of the helping verb is there after the fill-in gaps. This is ‘be’. We need to find the correct alternative which is contextually correct for the sentence along with ‘be’.