一般情况下,unless在意义上相当于if…not,两者可以互换使用,并且在意义上也无甚差别,只是unless的语气更强罢了.如:1.You will fail in the examination unlessyou study harder.(=You will fail in the exami-nation if you don’t study harder.)2.I’ll tell your father unless you come hereon time tomorrow. Under normal circumstances, unless is equivalent to if...not in the sense of meaning, both can be used interchangeably, and there is no difference in meaning, but the tone of absolute is stronger. Such as: 1.You will fail in the examination unlessyou study Harder.(=You will fail in the exami-nation if you don’t study harder.)2.I’ll tell your father unless you come hereon time tomorrow.