VOA一分钟英语：Unless 和 as long as 区别是什么？

单词 “unless” 和搭配 “as long as” 都可以用来表示一件事情发生的条件。虽然这两个说法非常相近，但它们的用法是有区别的。
 
Hi, I’m Georgina from BBC Learning English. In today’s lesson we look at the difference between unless and as long as.
Unless and as long as can be used to replace ‘if’ in different situations.
Let’s have a look at some example sentences.
I will go to the party if you come too.
I will go to the party as long as you come too.
Both of these sentences have the same meaning. Notice that the verb after ‘if’ and as long as is positive.
Now look at these sentences.
If you don’t do your homework, you can’t watch the film.
Unless you do your homework, you can’t watch the film.
Both of these sentences have the same meaning, but notice that the verb after ‘if’ is negative and the verb after unless is positive.
Bye!
 
用法总结
1 “Unless（除非）” 和 “as long as（只要）” 都可以用来引出一件事发生的条件，在不同的情况下，可代替 “if” 使用，而句意保持不变。
I will go to the party if you come too. = I will go to the party as long as you come too.
If you don’t do your homework, you can’t watch the film. = Unless you do your homework, you can’t watch the film.
 
2 搭配 “as long as” 的意思相当于 “if”，可以用来表达 “只要某条件符合，那么就...”。
I will go as long as you go. 
As long as we don’t make any loud noises, the baby will sleep fine.
 
3 单词 “unless” 的意思相当于 “if not”，可以用来表达 “除非某条件符合，否则就...”。
Unless I go home now, he’ll be worried.
We won’t be there on time unless this traffic clears quickly.