____ I win the lottery, I won't be able to buy a big house. a- If b- Unless

Solution:

• The sentence states a consequence of winning the lottery, which is not being able to buy a big house. This implies a contradiction or an unexpected outcome, suggesting that winning the lottery is the condition that prevents buying a big house. 'Unless' means 'if not', so 'Unless I win the lottery' means 'If I do not win the lottery'. The sentence implies that winning the lottery is the reason for *not* being able to buy the house, which is illogical. However, if the intended meaning is that winning the lottery enables buying a big house, then the sentence as written is incorrect. Assuming the intended meaning is a positive condition leading to a negative outcome or that the condition itself is negative, 'unless' would fit if the sentence were structured differently. Given the options and the likely intent (that winning the lottery usually allows for big purchases), there might be an error in the question's phrasing. If we interpret the sentence as 'If I *don't* win the lottery, I won't be able to buy a big house,' then 'unless' would be appropriate. However, as written, 'If I win the lottery...' sets up a condition. The outcome 'I won't be able to buy a big house' is contradictory to the usual implication of winning a lottery. Let's re-examine. 'Unless' means 'except if'. So, 'Unless I win the lottery, I won't be able to buy a big house' means 'If I don't win the lottery, I won't be able to buy a big house.' This makes logical sense. If you *do* win, you *can* buy the house. Therefore, the condition for *not* being able to buy is *not* winning.

Answer: b- Unless