unless 和 if…not 是具有多种功能的连接词,它们含有很丰富的、很细腻的词汇意义。unless 是由 on less e that 词组演变而成的,后来去掉了 that。on lesse 中的 on 是介词,其意义相当于 in;lesse 就是现代英语中的 less。on lesse 的意思是 in unless and if ... not is a connective with multiple functions, they contain very rich and very delicate vocabulary meaning. unless evolved from on less e that phrase, and later removed that. on onse on is a preposition, its meaning is equivalent to in; lesse is less in modern English. on lesse means in