but 和unless都做“除非，若不”时用法有区别吗？

答案是 unless

用but的时候。一般情况下，but后面的句子根前面有某种程度上的相反
ex: I want to go home, but I can't.
ex: The shoes are Nike brand, but they are fake
ex: This dress is fancy, but it doesn't fit me
unless就像是“除非” 需要除非。。后面的句子让句子成立
ex:sports shoes were not shoes unless they were Nike or Reebok

－nike和reebok牌子的鞋子才算是运动鞋，其他根本就不算
－运动鞋根本就不能说是鞋子，“除非”它们是nike或者reebok的牌子

我也解释不好。。。希望你能感觉的出不同哈``

A. but

1．unless conj．除非；若不；如果不……；除非在……时候
??You will fail to arrive there in time unless you start earlier．如果你不早点动身，你就不能及时赶到那儿。
??Unless bad weather stops me，I go for a walk every morning．除非天气不好，我每天早晨都要去散步。

??I won't loan you unless you are in extreme need of money．若不是你急需用钱，我不会借钱给你的。

??2．on condition that．．．只有在……条件下，以……为条件
??on condition引导的条件从句是主句中事件发生的前提条件或唯一条件。
??I can tell you the truth on condition that you promise to keep a secret．我可以告诉你真相，条件是你答应保守秘密。

??You can pass the