unless
conjunction /ənˈles/
/ənˈles/
- used to say that something can only happen or be true in a particular situation
除非；除非在…情况下 - You won't get paid for time off unless you have a doctor's note.
除非你有医生证明，否则你不上班便拿不到工资。 - I won't tell them—not unless you say I can.
我绝不告诉他们，除非你允许。 - Unless I'm mistaken, she was back at work yesterday.
除非是我记错了，她是昨天回来上班的。 - He hasn't got any hobbies—unless you call watching TV a hobby.
他没有什么爱好，除非你把看电视也称作爱好。
- You won't get paid for time off unless you have a doctor's note.
- used to give the only situation in which something will not happen or be true
若非；如果不 - I sleep with the window open unless it's really cold.
天气若不很冷，我总开着窗户睡觉。 - Unless something unexpected happens, I'll see you tomorrow.
如果不出意外，我明天去看你。 - Have a cup of tea—unless you'd prefer a cold drink?
喝杯茶吧，还是你喜欢冷饮？
Unless is used to talk about a situation that could happen, or something that could be true, in the future. If you know that something has not happened or that something is not true, use if… not If you weren't always in such a hurry (= but you are), your work would be much better. • Your work would be much better unless you were always in such a hurry. - I sleep with the window open unless it's really cold.
词源late Middle English: from on or in (assimilated through lack of stress to un-) + less.