常用过去完成时态,在这些词后接宾语从句或者接不定式的一般形式；或者用一般过去时态后面接不定式的完成形式表示过去未曾实现的愿望
17、比较句型：
(1)原级比较：
例：English is not so difficult a subject as Russia.
英语不是和像俄语一样难的科目。
Their bones are not as thick as adults’.
他们的骨头和成年人的不一样厚。
(2)一方超过另一方：
例：The weather of this year is a lot hotter than that of last year.
今年的气候比上一年的气候要热得多。
(3)一方不如另一方：
例：The restoration was so bad that it made some of the buildings less secure than they had been before.
修复工作是如此的糟，以致于它使得一些建筑没有以前安全了。
(4) The + ~er + S + V, ~~~ the + ~er + S + V ~~~
The + more + Adj + S + V, ~~~ the + more + Adj + S + V ~~~
（愈...愈...）
例：The harder you work, the more progress you make.
你愈努力，你愈进步。
The more books we read, the more learned we become.
我们书读愈多，我们愈有学问。
(5) more…. than…与其说…倒不如说
例：Smith is more diligent than intelligent.
与其说Smith聪明倒不如说他勤奋。
(6) no +形容词比较级+ than = as +形容词的反义词+ as
例：I am no better at English than you. 我的英语不比你好。
(7) that 在前后比较中代替不可数名词和特指的单数可数名词
例：The traditional picture of St Nicholas is quite different from that
of Father Christmas.
(8) one 在前后比较中代替泛指的单数可数名词。
例：I prefer a flat in Beijing to one in Nanjing, because I want to live near
my Mom's. 与南京相比我更喜欢在北京有一套公寓，因为我想跟我妈妈住一起。
(9) those 在前后比较中代替 特指的复数可数名词。
例：Salaries are higher here than those in my country.
这儿的工资比我们国家的高。
(10) ones 在前后比较中代替泛指的复数可数名词
例：Cars do cause us some health problems --- in fact far more serious ones
than mobile phones do.汽车确实给我们的身体健康带来问题，事实上比手机造成的问题更严重。
18、感叹句型：
(1) What a + Adj + N + S + V!
例：What an important thing it is to keep our promise!
信守我们的诺言是多么的重要啊！
(2) How + Adj + a + N + V!（多么...！）
例：How important a thing it is to keep our promise!
遵守诺言是多么重要的事！
(3) How + S + V!
例句：How I want to go to Beijing. 我多么想去北京啊！
19、表法猜测的句型：
(1) must have done sth 一定做过某事 否定形式：can't have done
例：She must have come here last night. 她一定是昨晚来的。
She can't have gone there 她不可能到那儿去。
(2) may have done sth 可能做过某事 否定形式：may not have done
例：Philip may have been hurt seriously in the car accident.
Philip 可能在这次车祸中伤得很严重。
(3) might have done sth 或许做过某事 否定形式: might not have done
例：She might have known what the bottle contained.
她或许知道这个瓶子里装的是什么。
(4) should have done sth 估计已经做了某事
否定形式：should not have done
例：She should have arrived in her office by now.
她此刻估计已经到达办公室了。
20、动词不定式常用句型：
(1) It takes / took / will take sb. some time / money to do sth.
某人花/花了/将花多长时间/多少钱做某事.
例句：It took me years of hard work to speak good English.
为了讲一口流利的英语,我花了多年时间刻苦操练.
(2) It is + adj +for/of sb to do sth
例：Lincoln said that it was not right for the South to break away from the
Union. 林肯说南方脱离联邦是不对的。
It was careless of Tom to break the cup.
(3) Sb. have / has / had no choice but to do... 某人除了做……别无选择.
例句：We had no choice but to take a taxi for we'd missed the last bus.
由于错过了最后一班公共汽车,除了乘坐的士,我们别无选择.
(4) It's not /just like sb. to do sth.……的行为不/正像某人的一贯作风.
例：lt's not like Jim to be late for class. He regards time as the most
important thing in life.
上课迟到不像吉姆的一贯作风,他把时间看作是生命中最重要的.
(5) ．．．．形容词／副词＋enough to do sth．
例：I was fortunate enough to travel to South Africa.．
(6) It pays to + V ~~~ （...是值得的。）
例句：It pays to help others. 帮助别人是值得的。
(7) It cost sb some time/money to do sth
例：It must cost a good deal to live here.住这儿一定会花很多钱的。
(8) do all he could to do sth
do what he could to do sth
do everything he could to do sth
例：They were doing everything they could to help the fatherland.
他们在尽最大努力去帮助祖国。
(9) It is hard to imagine/ say … 很难想象/说……
例：It is hard to imagine how Edison managed to work twenty hours each
day. 很难想象爱迪生每天是怎样工作20小时的。
It's hard to say whether the plan is practical.
这个计划是否实际很难说。
