Question

Fill in the blank with the appropriate modal:

He has lost your book and he ______ not tell you.

• A. need
• B. dare
• C. should
• D. must

Answer 1

The correct option is B dare

• Option B is the correct answer because 'dare' can mean 'challenge somebody’. With this meaning, it is a main verb and requires an object.
  

Dare also means ‘to be brave enough or rude enough to do something’.With this meaning, it can be used as an ordinary main verb which can be followed by a 'to'-infinitive or an infinitive without 'to' as in this statement, so 'he dare not tell you' is correct which means he was being brave enough to not confess.

• Option A is incorrect because 'need' means 'have need of, want or require' ,it also means 'to be under a necessity or obligation to do something'.
  

In this case, 'need not tell you' means it's not necessary to tell the truth, which is wrong.

• Option D stands the same explanation as for 'need' because 'must not tell' only means that it's not necessary to confess which is wrong.
• Option C is incorrect because 'he should not tell you' means the speaker suggests that the truth need not be told, which is wrong.