关于UnlessUnless表示if not.在新概念三第一课里有一句...,and experts confirmed that a puma will not attack a human being unless it is cornered.原句不是有个not了吗?把原句改成if not的形式怎么改呢?有这个疑问是因

关于UnlessUnless表示if not.在新概念三第一课里有一句...,and experts confirmed that a puma will not attack a human being unless it is cornered.原句不是有个not了吗?把原句改成if not的形式怎么改呢?有这个疑问是因
关于Unless
Unless表示if not.在新概念三第一课里有一句...,and experts confirmed that a puma will not attack a human being unless it is cornered.原句不是有个not了吗?把原句改成if not的形式怎么改呢?有这个疑问是因为看到一个选择题：
A:May I have the loan?
B:( )you offer good security.
A.But B.Unless C.Provided(if,正式) D.But for(要不是,虚拟)这里选C,因为B的话,对话就变成如果你不提供好的信用,你不可以贷款.
可能没说得很明白.呵呵

关于UnlessUnless表示if not.在新概念三第一课里有一句...,and experts confirmed that a puma will not attack a human being unless it is cornered.原句不是有个not了吗?把原句改成if not的形式怎么改呢?有这个疑问是因
给你下文吧：
UNLESS :
Not unless you offer good security.
PROVIDED:
（意味着 Yes,of course）Provided you offer good security.
注意：如果你要用 unless 前面非有 not 不可,明白吗?
More context for you,hope it helps:
Can I lend/use your computer?
A:Provided you don't damage it.
B:Not unless you promise/swear you won't damage it.

unless在意义上相当于if…not…，因此在有些场合if…not…可为unless所代替。
但在有些场合又不能互换，我们要注意下面几种情况：
1.当if…not…引导非真实条件分句时，一般不可改用unless。 例如：
If she had not had an alarm clock,she would have missedthe train.（事实：她有闹钟。）<...

全部展开

unless在意义上相当于if…not…，因此在有些场合if…not…可为unless所代替。
但在有些场合又不能互换，我们要注意下面几种情况：
1.当if…not…引导非真实条件分句时，一般不可改用unless。 例如：
If she had not had an alarm clock,she would have missedthe train.（事实：她有闹钟。）
如果把上述例句中的if…not…换成unless，意义就相反了。
（误）Unless she had had an alarm clock, she would havemissed the train.（事实：她没有闹钟）
2.If…not…引导的条件分句可以重叠使用，unless则不可， 因为unless表示唯一条件。例如：
She won't lose weight if she doesn't keep a diet and ifshe does not take exercise every day.
3.unless引导的分句可用否定结构，而if…not …引导的分句不可再否定。例如：
Don't ask me to explain unless you really don't understand.
The directors have a meeting every Friday,unless there is nothing to discuss.
以上两例句中的unless不可换成if…not…。
4.在unless引导的肯定形式的条件分句中， 通常用肯定词（即some,already,still,too,as well等），在if…not…引导的分句中，通常用非肯定词（即any,yet,ever,either,at all等）。例如：
I will criticize you if you haven't spoken to her yet.
I will criticize you unless you have already spoken to her.
（误）…unless you have spoken to her yet.
不过在否定形式的非真实条件分句中，if…not …结构仍能与肯定词连用。例如：
If he hadn't already prepared his lesson, he wouldn't beallowed to go.（因为这种从句表面上是否定，实际上是肯定。）
5.在间接引语中，当if=whether，意为“是否”，unless 不可以代替if…not…。例如：
She promised to let me know if she wasn't coming.
6.当unless含有“除了”的意思，不可为if…not…所替代。例如：
He never stammers,unless when he is angry.( unless when=except when)
Nothing will come out of it, unless disaster.(unless=except)
7.当主句是疑问句时，不可用unless代替if…not…。 因为unless用在A情况发生，必导致B结果之类的复合句中。例如：
What shall we do it they don't reply to our letters?
8.当主句谓语是be＋某些形容词或分词，如：glad,surprised,disappointed,satisfied,ashamed,delighted和pleased等， 不可用unless代替if…not…。例如：
I'll be really surprised if they don't come to the meeting.
I'll be quite glad if she doesn't join them.
之所以不能为unless代替，是强调否定条件的出现，表明在这种前题下的因果关系。以上条件状语从句都可变为原因状语从句。例如：
I'll be really surprised that they won't come to the meeting.
这里if被that代替了，而从句的否定结构不变。
综上所述，unless既等于if…not…，在某些场合又不相等， 因此要牢记它们之间的差别，准确地使用它们。

收起

unless表示除非，近义词 if not
选择题选b，unless强调了贷款条件