虚拟语气与非真实条件句

虚拟语气与非真实条件句的详解

1. with

With a little assistance, Alexander will succeed. (with=if he is given，表示真实条件，本句用的是陈述语气。)

2. in case of 万一

In case of fire, please dial this number. (in case of fire=if a fire breaks out，表示真实条件，本句用的是陈述语气。)

3. in the event of 如果……发生，万一

In the event of bad weather, we shall/will have to cancel the picnic. (in the event of bad weather=if the weather turns out bad, 表示真实条件，本句用的是陈述语气。)

二、介词或介词短语在非真实条件句中的运用：without, but for, in the absence of, under, but that等通常用在非真实条件句中，要用虚拟语气。

1. without

I would have failed in the examination without your help. (without=if it had not been for，表示同过去相反的非真实条件句，本句用的是虚拟语气。)

2. but for 要不是

But for your timely rescue, the boy would have drowned. (but for=if it had not been for, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

3. in the absence of 缺乏……时，当……不在时

In the absence of the keeper, the warehouse would have been burned down. (in the absence of the keeper=if the keeper had been absent, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

4. under

We might have done better in our research under more favorable conditions. (under= if we had worked under, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

5. but that 若非

But that your guidance, we should/would fail. (but that=if it were not for, 表示同现在相反的非真实条件，本句用的是虚拟语气。)

总之，可以替代if并构成含蓄条件句的介词和介词短语还有很多，我们在学习过程中，要注意观察和辨析，掌握好介词和介词短语在含蓄条件句里的真实条件句和非真实条件句中的运用。