Question

Fill in the blank with the most suitable option:
If you want to do well in life you _________ believe in yourself.

• A. can
• B. don't have to
• C. need
• D. must
  

Answer 1

The correct option is D must

Answer : D

Let's take a look at the usage of the verbs in the options:

• can : It is used to express an ability or lack of an ability / to give permission or express a prohibition / to make an informal request / to express a general possibility (only with positive verb) / to make a negative deduction
• don't have to : It is the negative form of "have to"; & is used to express that something is not a necessity / obligation; & is used to express absence of an obligation or necessity

• need : It is used to express a necessity or obligation / to express a requirement for something that is very essential

• must : to express a necessity (in the present or future); to make an assumption that something is true; to express an opinion about something that is logically very likely

Here in the question, we see that the speaker is expressing that to succeed in life it is a requisite, it is necessary that we believe in our-self. Therefore from among the options, 'must' is the most suitable verb to complete the sentence.

• "can" is NOT used to express an opinion or necessity or obligation, thus it is NOT suitable here.
• "don't have to" is NOT used to express an opinion or necessity or obligation, it is rather used to remove a necessity; and if we use it here it would completely change the meaning of the sentence.
• "need" is used to express a necessity or obligation but not an opinion about something logical, also it is used as "need to" and not only "need".

Thus, the correct complete sentence is:

If you want to do well in life you MUST believe in yourself.