You will be too tired to do homework ____ get enough sleep. a- if b- unless

Solution:

• The sentence implies that a lack of sleep is the reason for being too tired to do homework. 'Unless' means 'if not'. So, 'unless get enough sleep' is grammatically incorrect. The intended meaning is likely that if you don't get enough sleep, you'll be too tired. Alternatively, if 'unless' is used to mean 'except for', it doesn't fit here. If the sentence is intended to be 'You will be too tired to do homework if you don't get enough sleep', then 'unless' would be the correct word to fill the blank preceding 'you get enough sleep'. However, the blank is placed before 'get enough sleep', suggesting it directly modifies the action of getting sleep. A more natural phrasing would be 'You will be too tired to do homework if you don't get enough sleep'. Given the options, and interpreting the blank as needing a word that implies a negative condition for being too tired, 'unless' is the most fitting, assuming the sentence implicitly means 'unless you get enough sleep' (as in, 'if you don't get enough sleep').

Answer: b- unless