Question

Don’t get stuck in the Laki Pass at night. Once you’re there you ___________ get down and it’s very dangerous at night.
A) Don’t be able to
B) Can’t be able to
C) Not be able to
D) Won’t be able to

Answer 1

Hint: Modal verbs are verbs that are used to indicate the modality such as ability, likelihood, permission, request, capacity, suggestion, etc. Few examples of modal verbs are: can, could, may, might, will, would, shall and etc.

Complete answer:
Let us analyze the given options:
Option A) Don’t be able to – We use don’t when speaking in the first- and second-person plural and singular and third-person plural. Thus, the use of don’t in the blank will make the sentence grammatically incorrect and thus, this is an incorrect answer.
Option B) Can’t be able to – We use can’t in the informal form of writing. Can’t talk about the possibility of the situation and there is no such possibility. Therefore, this is an incorrect answer.
Option C) Not be able to - Don’t get stuck in the Laki Pass at night. Once you’re there you are not able to get down and it’s very dangerous at night making the sentence grammatically incorrect and thus, this is an incorrect answer.
Option D) Won’t be able to – Won’t states will not. We use won’t in more informal writing. Thus, the use of won’t is the most appropriate word in the sentence as it makes the sentence grammatically correct and therefore, this is the correct answer.

Thus the correct answer is option ‘D’ i.e, Don’t get stuck in the Laki Pass at night. Once you’re there you won’t be able to get down and it’s very dangerous at night.

Note: Modal verb is the verb that expresses the attitude of the speaker to what is being said. The given sentence in the question requires a modal verb that to be in the future tense. Option D is the most appropriate answer because "won't be able to" defines a state of caution in future. Whereas option A, B, C do not serve the necessary mood of the writing.