A conditional sentence is commonly composed of two parts:
conditional clause and main clause. There are four types in the
conditional sentence. TypeⅠ is a kind of real conditional. It is
also called “whenever type” in that “if” here is used in the sense
of “whenever type”. TypeⅡ is the commonest of real conditionals.
This type falls into three forms: basic form, variant form, and
alternative form. TypeⅢ is a sort of unreal conditional. The
probability of the condition varies in degree with different
contexts or situations. TypeⅣ is the unreal conditional that is
completely hypothetical and represents what is contrary to past
fact.
If the train _is_ (be) on time, it will be here in ten
minutes.
本句话是将从现的用法。
If I _were earning_ (earn) s good salary, I wouldn’t think of
changing my job.
后半句说明是与现在事实相反的，所以前面用现在进行时。
If you _were to stay_ (stay) in England just a few months longer,
your English would probably show a noticeable improvement.
后半句说明与将来事实相反，所以前面也用与将来事实相反的。
If only he _would admit_ (admit) he was wrong, his friends might be
more sympathetic.
从句中用would+不定式，表示不大可能实现的“意愿”。
If he _would lift_ (lift) a finger to help me, I would be sure of
success.
从句中用would+不定式，表示不大可能实现的“意愿”。
As the sun was in the right direction, the photographs came out
very well.
If it hah not been for the fact that the sun was in the right
direction, the photographs would not have come out so well.
改写时要注意加上 the fact that，连接起虚拟的模式。
The Government raised taxes, so they were very unpopular.
If the Government had not raised taxes, they would not have been so
unpopular.
要注意在该虚拟语气的时候，要注意前后句子的否定情况，不可以随意改变句意。
There was a very sharp frost last night, so we’re able to go
skating today.
If there had not been a very sharp frost last night, we would not
be able to go skating today.
要注意在该虚拟语气的时候，要注意前后句子的否定情况，不可以随意改变句意。
If you _would_ kindly _take_ (take) me in your car, I shall be able
to get to the hospital on time.
与现在事实相反，所以要用would do。
Little is known of his childhood _C___ at a factory at the early
age of ten.
A. to begin to work B. beginning to work C.
save that he began to work D. about that he
worked
此处save为介词，相当于except，但不太通俗，其后除接名词或代词外，也可接that 引导的从句。
There is a general understanding among the members of the Board of
Directors that chief attention _C___to the undertaking that is
expected to bring highest profit.
A. is given B. gives C. should be given
D. must be given
understanding 如同suggestion, motion, plan, idea,
order等词一样，其后的同位语从句中的谓语动词须用虚拟语气，should加原形动词或直接用原形动词。
They did not find _B___to prepare for the worst conditions they
might meet.
A. worth their while B. it worthwhile C. it worth
D. it worthy
在find it worthwhile to prepare …中，find之后是一个复合结构，其中it是形式宾语，真正的宾语是to
prepare, worthwhile （值得花时间的）是宾语补足语。
Quarter horses can start more quickly, turn more sharply, and run
faster over short courses _C___ breeds can.
A. than the other B. other C. than other D.
of all other
than other breeds can 是一个比较状语从句，与前边的more quickly， more sharply，
faster 等相呼应。A)，D)本身是错的，B)无比较意思。
Most insurance agents would rather you _B___ anything about
collecting claims until they investigate the situation.
A. do B. didn’t do C. don’t
D. didn’t
would rather 后跟的从句用动词过去时，表示“宁愿别人…”，而C)和D)无实义动词，故B)是正确的。
“I’m surely dirty, _C___?”
A. am I B. isn’t I C. aren’t I
D. am not I
“I am+表语”这一结构的反意疑问句是一固定结构，即aren’t I。
_C___illness, he retired.
A. Thanks to B. According to C.
Owing to D. For the sake of
owing to意为“由于，因为”；thanks to意为“幸亏”；according to意为“根据”；for the sake
of意为“为了…”。
This car has many features including __D__.
A. stereo, safety devices, air condition, and it saves gas
B. good music, safe devices, air conditioning,and gas
C. stereo, safety devices, air conditioned and good gas
D. stereo, safety devices, air conditioning, and low gas
mileage
此题测试平行结构。所谓平行结构指的是句子的并列成分在结构上应该一致或相同。A)中it saves gas
为句子。B)中尽管各成分在结构上等同，但逻辑意义上不成立，gas指“汽油”，凡汽车皆有，不能构成该车的特点。C)中各成分尽管结构等同，但表示的意义并不指该车的特点。
Every boy and girl must have _A___ hair neatly combed.
A. his B. her C. its
D. their
当我们提到两个单数名词，一个是阳性，另一个是阴性，它们由and 相联，并由each
或every所修饰时，其物主代词应为his。
I wish you_D___ Jim so much. He is still very depressed.
A. not to hurt B. didn’t hurt C.
would not D. had not hurt
此题测试wish后虚拟语气表示的不同含义；wish后面可跟复合结构，只有否定形式的过去虚拟语气D)had not hurt
才符合题意。
在这节课上我们学了条件从句，类型三和类型四其实就是我们过去所说的虚拟语气的用法，类型二就是主将从现和它所引出的一些变化。类型一中需要记住事实公理客观存在的就要用一般现在时，过去习惯的动作要用过去时。
