第 110 课 · 第 9 阶段: 连接观点
“unless / in case / as long as”
中级“Unless / in case / as long as”
构成与用法
unless, in case, as long as, provided that, even if — 表达条件的其他方式
1.概述
除了 if，英语还有好几个表示条件的连接词，每个都有自己的意思。
| 连接词 | 意思 | 例句 |
|---|---|---|
| unless | 除非（= if … not） | I'll walk unless it rains. |
| in case | 以防（因为某事可能发生） | Take a jacket in case it gets cold. |
| as long as / so long as | 只要（满足这个条件） | You can go as long as you're back by ten. |
| provided (that) / providing (that) | 只要（更正式） | You can park here provided you have a permit. |
| even if | 即使（不管这件事发不发生） | I'll go even if it rains. |
和 if 一样，这些词后面都用现在时表示将来，不用 will：in case it rains（不说：in case it will rain），unless you come（不说：unless you will come）。
2.Unless = if … not
Unless 本身已经含有否定意思（“如果不”“除非”），所以后面的动词通常是肯定形式。
Unless we leave now, we'll be late.
除非我们现在就走，否则会迟到。（= If we don't leave now…）
I won't call you unless there's a problem.
除非有问题，否则我不会给你打电话。
Don't touch that unless you know what you're doing.
除非你知道自己在做什么，否则别碰那个。
Do you need a coat? — Not unless it gets really cold.
你需要外套吗？——除非天特别冷，否则不用。
- 当条件是唯一的例外时才用 unless。有些 if … not 的句子不能换成 unless，特别是表达对某事没有发生的感受时：I'll be upset if you don't come（不说：unless you come）。
- 疑问句一般用 if，不用 unless：What will you do if you don't pass?
3.In case = 以防
In case 说明现在做某事的原因：为以后可能发生的事做好准备。
Save the file now in case the computer crashes.
现在就保存文件，以防电脑死机。
Take a photo of your passport in case you lose it.
把护照拍张照，以防丢了。
In case 和 if 不一样。比较：
I'll cook extra rice in case your friends come.
我多煮点饭，以防你朋友来。（不管他们来不来，我现在都煮）
I'll cook extra rice if your friends come.
如果你朋友来，我就多煮点饭。（他们来了我才煮）
- just in case = 以防万一（可能性更小）：I don't think we'll need it, but I'll bring a charger just in case。
- in case + 过去时 解释你过去做某事的原因：I gave her my number in case she needed help。
- in case of + 名词 = 如果发生……（常见于标志和说明）：In case of fire, use the stairs。
- 在美式英语中，in case 有时用起来几乎和 if 一样：In case you need me, I'm in my office。学习时，最好按上面的方法把两种意思分开。
4.As long as / provided (that)
这几个词表示严格的条件：只有满足这个条件，结果才会发生。As long as / so long as 在口语中很常见；provided (that) / providing (that) 更正式，常见于规定和合同。
You can borrow my laptop as long as you're careful with it.
只要你小心使用，就可以借我的笔记本电脑。
As long as you practise every day, your speaking will improve.
只要每天练习，你的口语就会进步。
Guests may use the pool provided that they shower first.
客人须先淋浴，方可使用泳池。
I'll lend you the money, providing you pay me back next month.
我借钱给你，只要你下个月还我。
As long as 也可以表示时间，“在……的整个期间”：You can stay as long as you like。要读完整句话，才能判断它表示条件还是时长。
5.Even if = 不管会不会
Even if 表示不管条件是否发生，结果都一样。不要和 even though 混淆，even though 说的是事实（见“Although / though / despite”一课）。
I'm going to the beach even if it rains.
即使下雨，我也要去海边。（我们还不知道会不会下雨）
Even if we leave now, we won't get there on time.
即使我们现在就走，也来不及准时赶到了。
Even though it was raining, we went to the beach.
尽管在下雨，我们还是去了海边。（当时确实在下雨）
6.常见错误
Unless you don't study, you will fail the test.Unless you study, you will fail the test. / If you don't study, you will fail the test.
Unless 本身已经含有否定意思。
Bring a jacket in case it will get cold.Bring a jacket in case it gets cold.
in case 后面用现在时表示将来。
I won't go unless you will come with me.I won't go unless you come with me.
unless 后面不用 will。
Take an umbrella in case of it rains.Take an umbrella in case it rains. / … in case of rain.
In case + 从句；in case of + 名词。
Even it rains, we'll play football.Even if it rains, we'll play football.
要用 even if，不能只用 even。
Even though it rains tomorrow, I'll go.Even if it rains tomorrow, I'll go.
不知道会不会下雨 → 用 even if。
例句
- You can't come in unless you have a ticket.
- Unless you hurry, you'll miss the bus.
- We'll have the party in the garden unless it rains.
- Take an umbrella in case it rains later.
