一、 教法建议
抛砖引玉
同学们通过本单元课文“A Problem For The Detective”，可以看到课文中所鞭挞的
尔虞我诈的丑恶现象，同时受到深刻的教育。为人要诚实，遵纪守法，要有社会道德。
单元双基学习目标
Ⅰ.词汇学习
step(vi)will(n.)step-mother,check out,afterwards,go through,look into,build up,wealthy,divided up,anyway,private,left-handed,right-handed,brief,to the point,foresee,instruct,signature
Possibility and impossibility
may(not) do…
is likely that…/It is possible that…/She is mot likely to do…
this building be 17th centruy?
you mind if I bring a friend along with me nest time?
you be able to come to the Party?
d it be possible to do…
looks as if/though it might rain later.
'll probably do…/I doubt if…
appears to me that we'll have to go on foot.
's/It's quite impossible./It's very unlikely./That's hardly possible./That'll never happen./Probable not.
Ⅲ.语法学习
在这一单元，同学们要学习归纳定语的使用。在高考测试中，经常出现一个名词的前面
被几个形容词所修饰的情况，形容词的排列是有一定的顺序性的。大致为：
限定词(all,twice,a,this,my,each,three,last)銮炕形容词(certain,perfect,comp
lete,slight,extreme)雒杌嫘曰蛘咧鞴燮兰刍蛘咧柿啃稳荽(expensive,beautiful,fine,
brave,dirty)霰硎敬蟆⑿ ⒊ぁ⒍獭⒏叩偷男稳荽(large,small,litle,long,short,tall,high)霰硎拘巫吹男稳荽(round,straight,aquare,flat)霰硎灸炅洹⑿戮傻男稳荽(old,young,new,modern)霰硎狙丈的形容词(如：red,green,brown)霰硎竟家、出处、来源的形容词(French,Chinese)霰硎疚镏省⒉牧系男稳荽(wooden,stone,plastic,brick)霰硎居猛尽⒗啾鸬男稳荽(medical,sports,evening,story)雒词。
指点迷津
表示原因和进行意义的介词(短语)
(一)表示原因的介词
use of 表示引起结果的直接原因，意义与连词because相同。
He retired last month because of illness/because he ill.
表示内在的、心理上的原因，常与表示喜、怒、哀、乐等情感名词连用；还可表
示某种动作或结果的起因。而连词for则表示某种结果的补充理由或显而易见的原因。
He trembled for fear.
Thank you for your help.
When he was still a young man,he was forced to leave his homeland for political reasons.
表示外部的，尤其是暴力的或无意中造成某种结果的原因。
Her body was bent by age.
The general died by his own hand.
She took your umbrella by mistake.
表示某种情绪或动作的原因，多与“喜，怒，哀，乐”等义的词连用，常译作“听到……”，“看到……”。
The whole nation was in deep sorrow at the news.
He jumped at the news.
表示能作为依据或条件的原因，常译为“依照……”。
He has given up smoking on medical advice.
和from表原因时常与die类似意义的词连用。die of指因疾病，冻饿，或害怕，羞愧等内因或外因造成的死亡。与疾病名词连用时，二者均可。from还可表示懒惰等造成某种后果的原因。
His son having been killed in the war,the man died of a broken heart.
In big cities during cold winter months,many old people die from the polluted air.
She died of/from cancer.
He wasn't ill;he stayed in bed from laziness.
指生理上或情感上的由外界到内心的原因，意为“随着……”。
The man bent with age.
He turned red with anger.
表示引起某种状态或过程的原因。
He is rolling on the floor in pain.
He rejoiced in his own success.
g to,相当于because of,多表示引起某不良后果的原因。
Owing to the rain they could not come.
Owing to his lacking on experience,John failed this time.
注：owing to 也可表示“欠……钱”之意
How much is he owing to you?
ks to 表示引起某种幸运结果的原因，常译为“幸亏……，多亏……”。
Thanks to the timely rain,the farmer had a good harvest.
of 表示动机的起因，常译为“出于……”。
He asked the question out of curiosity.
He did it out of pity.
ugh多表示因局部而影响全局的原因。
The war was lost through bad organization.战争因组织不周而失败了。
(二)表示进行意义的介词
+(the)+名词：at table(在用餐)，at war (战时)，at peace(和平时期)，at press(正在排印)，at one's meals(在吃饭)，at one's study(在学习)，at work(在工作)，at the piano (在弹钢琴)，at the end (of)(在结束时)。例如：
These boys are at play (=fully blooming).
The surgeon fainted at the operation.
+(the)+名词：in reading(正在阅读)，in politics(从事政治活动)，in the course of(在……过程中)，in the act of (正在做某事)。例如：
The flowers are in full bloom (=fully blooming).
He was in the army.
+(the)+名词：on duty(在值日)，on business(在办事)，on guard(在值勤)，on leave(在休假)，on a walk(在散步)，on watch(在⑼)，on service(在服役)，on holiday (在度假)，on strike(在罢工)，on sale (出售)，on loan(出借)，on the boil(<水〉正在开)，,on the move (在移动，搬迁，离开)，on the march(在行军)，on the watch/look-out (在警戒)，on the flow(在涨潮)，on the turn(在转折中)，on the wing flying (在飞行中)，on the advance/rise(〈行市〉看涨)，on the increase (正在增加)，on the go (正在活动，正在奔走)，on the air (正在广播)，on the fly (正在飞行)，on the way (在途中)。
The house is on fire.
They saw the enemy soldiers on the run.(=running)
r+(the)+名词：under the doctor (在医生的照顾下)，under test/exam(在被测试)，under development(在发展中)，under construction(在建设中)，under repair(在修理中)，under consideration (在考虑中)，under observation (在观察中)，under discussion(正在被讨论)，under the agreement (根据协议)，under orders(听从命令)。
He is working under my father.
Several new railways are under construction in China.
二、 学海导航
学法指要
单元重点词汇点拨
thy富裕的，富有的，有钱的
He succeeded in business and was very wealthy,他事业成功，非常富有。
wealthy 的词形式是wealth,是不可数名词。如：
She has a wealth of knowledge about plants.
She has great health.=She is a women of great wealth.
另外要注意：be wealthy in=be rich in 在……丰富。如：
China is a developing country;she is wealthy in natural resources.
ay=anyhow无论如何
He may not like my visit,but I shall go and see him anyway.
Anyhow I must finish the work today.
I may fail,but I shall try hard anyway.
用让步状语从句表示时可用：wh-ever…/No matter+wh-…。如：
No matter how hard he works (However hard he works),he still makes little progress.
f简短的；简洁的
She left a brief note.
His explanation was brief and to the point.他的解释既简洁又切中问题的要点。
固定词组to be brief=in short简单地，扼要说明。in brief=briefly=to put it briefly 简言之；简单地说。
To be brief,she was happy with that result.
Please tell me briefly what happened.
单元词组思维运用
into=enter=walk into 步如
the way顺便告诉你；顺便问一下
d up a large business 建立一个大企业
one's will在某人的遗嘱中。at will随意地，随心所欲地。against one's will 违背本意，无可奈何地。如：
He practicing skating at will.
He obeyed the order against his will.
t from =except除了
the burial services在葬礼上。at the marriage services在婚礼上。
de up 分掉
out a lot 经常外出
k out 查明
a start 首先
into the case调查这个案子
k as follows讲了这样的话
a false name冒名
a visit to sb 去看望某人
brief and to the point谈话简明扼要；直截了当
an appointment with sb与某人约会
单元难点疑点思路明晰
she's left about $4 million in her will to her husband's daughter by his marriage.在她的遗嘱中，她已把大约4百万美元留给了她丈夫第一次结婚所生的女儿。
(1)leave sth to sb把某物留给某人；in one's will 在某人的遗嘱中；by marriage通过姻亲关系。
(2)marriage是动词marry的名词n.结婚；婚姻；婚姻生活；婚礼v.如：
be related by marriage有姻亲关系；give sb in marriage to把某人嫁出；take sb in marriage娶某人；嫁给某人。
2.I want you to check out this clare Flower…我想要你核实一下这位克莱尔弗劳尔记手续。如：
The skilled driver checked out the motor.
Guests must check out before noon,or they will be charged for the day.
a start,how old was she whem her father married again?首先，她父亲再婚时她多大?
for a start首先；一开始。如：
For a start,you're to young.
you go through them and give me whatever you find? 你能否翻一翻这些文件，然后把你找到的所有东西给我。
(1)go through仔细检查；济览，翻阅；搜查；穿过，通过；经历，经受，忍受。如：
I went through the papers looking for Jane's letter.
(2)whatever 在此作宾语，不能换作no matter what.当二者作状语时可以换用。
Flower directed that all the money that belong to her should come to you.弗劳尔太太指示要把所有属于她的钱留给你。
direct指示；命令；导演；指导；给……指路。如：
The general directed/ordered that the prisoners should be set free.
The medicine should be taken as directed by the doctor.
't tell me that all this is because of photograph taken when I was twelve.别告诉我所有这一切是因我十二岁时拍的一张照片。
(1)all this所有这一切。all作形容词“所有的，全部的”时，可与单数名(代)词连用，起加强语气作用。如：
all China 全中国，do good all one's life一辈子做好事。
(2)taken when…为过去分词短语作photograph的后置定语。
instructed in her will that if that were to happen.她在遗嘱中指示，如果此事发生的话……
instruct指示，命令；教育；通向。如：instruct(或direct,order)sb to do sth指示命令做某事。
lawyer was brief and to the point.律师说话简单扼要，直截了当。
to the point 中肯；贴题；扼要。常在句首作插入语。已学过的类似结构还有：to tell you the truth说真的，to be brief简而言之；to be honest说实在的；to begin with 首先，第一；to make a long story short 长话短说，简而言之；to sum up总之。
thy,rich,plentiful
wealthy 财富极多，暗示财有道，有多高的社会地位。如：
Power is in the hands of the wealthy in the west.
“富裕的，有钱的”指人的财物超过正常需要标准，用于物时指含量或蕴藏丰富，也可指精神世界。如：
The Chinese diet is rich is fibre and low in sugar and fat.
plentiful“丰富的，充足的”多指提供的物质、钱财等非常充足。如：
a plentiful supply of food 丰富的食品供应
de up, divide into,divide among,divide by
divide into分成。如：
Let's divide ourselves into two groups.
The boy divided the cake into six picecs.
divide among在……中间分。如：
The teacher divided the biscuits among his students.
divide by被除。如：divide 20 by4.4除20/6divided by 2 equals 3.6被2除等于3。
into,look in
(1)look into向……里面看去；窥视；调查；观察。如：
The x-rays allow a workman to look a thick steel plate.
Please send more researchers to look into this product.
(2)look in 往里看；顺便看望(+on sb).如：
That's my room. Look in,please.
Won't you look in on me next time you're in town?
ate私有的；个人的；秘密的。该词可作形容词和名词含不易公开之意。如：
ask for leave on private affairs私事请假；talk with sb in private同某人私下交谈；a private letter 私人信件；a private room 单人房间。
personal个人的，私人的；人称的；直接的。如：
personal opinion个人的意见；have a personal interview with和……直接面谈；personal pronoun人称代词。
of age,be of an age
(1)be of age成年。而be under age 未成年。如：
My daughter is of age but his is still under age.
(2)be of an age=be of the same age同龄。如：
He and I are of an age.
妙文赏析
Once upon a time an African king left his country to make a long trip,and he
told one of his guards(1)his treasure the guard was(2)by the riches of
the room and began to steal the(3) (4)some of boxes of gold and silver and (5)and (6)them with some the king(7),he praised the guard for his(8)to duty and sent him before long he(9)what the guard had done.(10)punishing him,he called him back to his(11)and told him (12)He said,“(13)a snake crawled(爬)in a farm house and found an (14)jug(罐子)of drand and drank(15)he was (16)fat to crawl back through the neck of the ver,what must that that snake(17)to get out of the jug?”
“He must spit out the(18),”the guard answered.
“(19),”the king said,“(20)he spit out out all of it?”
“I think he will (21)spit out all of it to get out.”
“You are(22),”the king said.“(23)”.
The guard looked around and saw many (24)with spears(25)back and forth in the palace,he knew everything.
observe hing out take care of build
ed ted nished ding
's ces
d fond of ied
sure sty ls queen
w ged king ed
d it rned ht him
tion ake ship
sed overed itted uraged
ead of spite of
sure ce ession
12.A.a story to do law D.a puzzle
e htened ng
t
use r l that
er cially ming
k out
g
know nothing
can ld t
his best the way to
ht shed ainly e right
ht me C.I'll kill you of it
ls es iers cemen
ding ing ding ting
答案与简析
1.C。tell do sth.是tell带复合宾语的固定句型；take care of是一动词短语，意为“照看”，填入C项句型结构与句意均正确。2.B。由空白后的by the riches of the room and began to steal the King's treasure 可以确定，此空应填B。句子主语是谓语动词动作的承受者应用被动语态，此外tempted为过去分词。3.A。短文第一段叙述了从前一位非洲国王离开国家去作长途旅游，我们再根据he told one of his guards to take care of his treasure room及第二段第一句中But the guard was tempted by the riches of the room.就可以判断出，这位卫兵所偷的是国王的珍宝。4.D。由and后并列的谓语filled them with some stones可以推断出，此空应填emptied,表示“倒空”。5.C。上文叙述了卫兵began to steal the King's treasure,而gold,silver和jewels均属于珍宝，故先C。6.D。fill… with… 是一固定的动词短语，意为“把……装满……”。这个意思可以从前一个并列分句He emptied some of the boxes of gold and silver and jewels判断出来，这句意思是卫兵把箱子里的珍宝倒空，而装入石头取而代之。7.B。主句he praised the guard .A。devotion to duty 是一名词性短语，意为“忠于职守”。for his devotion to duty and sent him away表明，此空应填returned,表示“返回”。8.A。devotion to duty 是一名词性短语，意为“忠于职守”。9.B。由下文国王召回卫兵，通过讲故事的手法启发他交还所偷珍宝，可以推断出此空应填discovered,说明国王已发现了卫兵的盗窃行为。10.B。instead of是一短的语介词，后跟动名词，表示句子主谓结构所表示的动作代替介词短语后的动作。这里指国王发现了卫兵盗窃珍宝后，不是用惩罚的办法，而是把他召回，用讲故事的方法，启发他偷了东西该怎么做。11.B。持续性动词在同until搭配时，用肯定式表示动作持续，意为“到……为止”，填入C项与句意相符。16.A。“too+adj.+to do”是一固定句型，意为“太……而不能……”，其中不定式修饰副词too作目的状语，具有否定意义。17.A。由空白后的作目的状语的动词不定式to get out of the jug,可以判断出此空应填do,这里表示“办法”。18.C。四个选项的名词填入空白语法都正确，我们读了上文Once a snake crawled into a farm house and found an open jug of drand and drank until he was too fat to crawl back through the neck of the jug.就不难判断出答案先C了。19.D。这里通过讲故事，让卫兵寻求牛奶如何出罐的办法。填入D项表明国王非常同意卫兵的答话“He must spit out the milk”.20.C。该句国王用反问的手法，进一步强调卫兵答语的正确性，故填should。21.D。由上文He drank and drank until he was too fat to crawl back through the neck of the jug.可以判断出此空为D,have to 带有客观因素，意思是“不得不”。22.D。填入D项表示国王非常同意卫兵说的“I think he will have to spit out all of it to get out.”这一观点。23.D。这里国王重复卫兵答话中的all of it,是用比喻的手法来提醒卫兵归还所盗窃的全部珍宝。24.C。空白后的with spears walking back and forth in the palace 已作出暗示，卫兵看到的许多人正是士后。25.B。四个选项的现在分词填入空白，都可以作with复合结构的宾语补足语，但根据空白后表方式的状语back and forth可以确定，正确答案为B。
思维体操
Riddle
is the leter G like the sun?
is the letter T like island?
is U the happiest letter?
h letter is most useful to a deaf woman?
letter in the alphabet can travel the greatest distance?
is the end of everything?
what way are the letter O and E neatly keep house alike?
does the letter B do for boys as they grow up?
is a sewing machine like letter S?
is a false friend like the letter P?
答案：use it is the center of use it is in the middle of use it is always in the midst of letter A, because it makes HER letter D, because it goes to the end of the are always in they grow older it makes them use it makes needles needless.
三、智能显示
心中有数
单元语法发散思维
哪些成分可以作定语?
1.形容词
His father is an advanced worker.
He told us an interesting story.
The marked the students absent.
2.代词
Our town becomes more and more beautiful.
3.数词
The Yellow River is the second longest river in China.
More than three hundred students visited the Great Wall.
4.名词或者名词所有格
She gets used to the country life.
These are childrens'books.
5.过去分词短语或者动词-ing短语
The man waiting outside is a new comer.
Is there anything planned for this evening?
6.不定式
He has no food to eat
Has he a house to live in?
She has no friends to talk with.
7.介词短语
The woman of great wealth is my niece.
8.定语从句
This is the place where he works.
动脑动手
单元能力立体检测
(一)给下列每个句子填上一个恰当的介词或副词
girl said “Bye-bye!”and then rang .
se go and tell him to turn the 's too noisy!
3.I can't get to his line is busy.
you mind if I point the mistakes in you composition?
't plant rice year year in the same field.
a result of the dam,the water level of the lake was going to rise
63meters.
7.I'd prefer to take a rest at home today.I don't feel walking very much.
on lies the rive Thames and has a population of seven million.
Communist Manifesto closed words that quickly became famous:“Working people of all countries,unite!”
woodcutter was standing next to a fallen tree, lots of small pieces of wood in front of him.
答案：。ring off“挂断电话；停止讲话”。 down 关小，turn up 开大。ugh。get through 打通电话；到达；通过。 。point out指出，point to指向，point at 瞄向。 by year逐年(含有新变化)，year after year年复一年(含年年如此的重复)。 。by可表“相差”之意。又如：increase by30%增加百分之三十。。feel like+ing很想干……，would like/love+to do 很愿干……。 。on可以表达“在……河畔”。。in words 口头上，in a/one word 总而言之，with words用语言，in other words也就是说。 。
(二)定语从句练习
you know the girl necklace has been stolen?
h e
she came back from London,she told us about the schools and teachers
she had visited.
h e
is the boy is speaking there
h
d is one of the foreign teachers who in China.
working worked
d is the only one of the foreign teachers who in our county.
working s worked
this factory we visited last year?
e one h
this the factory we visited last year?
e one
notebook cover is red is mine.
h e
is the very book I badly need.
which h
e was nothing in the world he was afraid of
h e e
11.I found little he didn't know about history.
e h
is the third city the foreign friends have paid a visit to.
e h which
best books I borrowed from the library are all here.
h ever
last place the foreign guests called at in China was Hangzhou.
e h which
man I am going to meet at the station is Professor Smith.
whom ver e
答案：1-5DBCDA 6-10CDCBB 11-15CCBDC
创新园地
下面表格中的词组选自本单元，请同学们结合对课文的理解完成英语译文：
divide up apart from go through turn up check out
as follows pick out build up pretend to do for a start
1.通过十年的努力，他创建了一个2，000人的电脑公司。
2.去核实一下是否在11点有列车开往北京。
3.8点钟时，大人物们都一一登场了。
4.除此之外，你没有其他理由拒绝做这件事。
5.她嚎啕大哭，假装伤的不轻。
6.教师选出了最好的乒乓球运动员。
7.请尽快把整篇文章通览一遍。
8.首先，我想作一简单的介绍。
9.她写的内容如下。
10.我们怎样分工?
答案： 10 years of hard work,he has build up a computer company of 2,000 people. se go and check out whether there is a train to Beijing at 11 o'clock. 8 o'clock,all the VIPs turned up. t from this,there is no other reason for you to refuse to do it. cried hard and pretended to be badly hurt. teacher picked out the best table-tennis players. se go through the whole text as quickly as possible. a start,I'd like to say a few words about myself. wrote as follows. can we divide up the work?
四、同步题库
(一)单词拼写
cousin keeps dozens of (goose)on that pond.
our opinion,it is easy to raise (ox)in these villages.
about asking them to carry their (luggage)upstairs?
than one (housewife)attended this meeting.
has a terrible illness,which is a (hope)case.
Twain was a (humour)writer,as is known to all.
e are many wild birds in this (mountain)area.
beauty of that lake is beyond (advantage).
as it is,it has its (advantage).
has been proved that she is a (fail)as a waitress.
was p at the meeting for having done a lot of good deeds.
you sure about the meaning of the i “put away”?
country has many i ,the largest of which is Taiwan.
and is s from France by the English Channel.
looked p ,for he didn't understand what I said.
sister-in-law is of American (国籍)。
n go to church (定期地).
Sixie was one of the (先驱)of farming in the 16th century.
you mind (重复)what you said just now?
improved her spoken English by (练习)speaking it every day.
(二)根据汉语提示，完成下列翻译
day he (偶然遇到)one of his old friends when he was on the way home.
I (聊一聊)you about your English composition?
(取得如此迅速的进步)jumping that before long he got the first place in the competition.
ough they work in different cities,they still (保持密切联系)one another.
(就要)leave when it began to rain.
e facts suggest that man (不能违背)the law of nature.
at the back cover of the does “ISBN” (代表)?
United States of America is a large country,which (构成)50 states.
one should (轻视)those children who are deaf,lame or dumb.
reaching the meeting room,she was (气喘嘘嘘)。
(三)情态动词练习
him, but she didn't choose to.
have told t have told have told have told
2.-Your telephone number again? I quite catch what you said.
-It's 99886644.
't dn't 't 't
you be sitting is this waiting-room. It is for women and children
only.
tn't to 't 't 't
you really want yourself to be in good health,you must always so much.
;have smoked ;to smoke
not;smoking ,be smoking
5.I didn't see her in the meeting-room this at the meeting.
n't have spoken ldn't have spoken
dn't have spoken n't have spoken
6.-would it bother you if I talked to you for a minute?
- .
,please at all ,I don't ,please don't
are doing in a wrong tis way.
to do used to to be done used to doing
8.-Are you a football player?
- .
,I'm used to being .I used to be
,I used to be a player ,don't mention it
e used to be a church in the west of the town, ?
n't to there n't it 't there 't there
10.- I use your bike,Tom?
-Sure,you .
d;can ;could l;can d;could
11.-Has Jane arrived yet?
-No,she .
have returned ld return
supposed to have returned t to return
learned to speak the language to quickly and well that he for a native speaker.
have been taken ld have been taken
d have been taken have been taken
,you are so lazy!This work hours ago.
ld finish have finished
t have finished t to have been finished
14.-Professor Wu,a lot of students want to see you.
- they wait here or outside?
l d
eve it or not,there be a cinema to the north of our school.
to d t
16.-You ought to have called her the day before yesterday.
-Yes.I know I .
ld t to k so t to have
was told that she not take up the examination.
t to to ed
18.-Have you done your homework?
-On the contrary,I had better last night.
sh finished finish shing
car sped towards the cat quickly,but it escape.
to d able to d
't enter the office without our manager's permission, ?
you you you you
答案：(一)e age ewife less rous
tainous ription dvantage ure sed m nds rated led onality larly eers ating ticing
(二) across,也可写成ran into,came upon,met by chance a talk/word with such rapid progress in in close touch with about to 't go against d for made up of down on/upon of breath.因要求与词组，故不用breathlessly。
(三)1.B。从后部的时态看应是“当时有可能告诉”。2.A。从again表明应是指说话前
的事实性动作，不表能力。3.A。情态动词与进行时连用表达逼真的感情色彩，这里含“不
应该总是坐在……”4.D。含讨厌的色彩。5.C。对过去的否定推测常用can't/couldn't+have+过去分词。6.B。7.C。used to do “过去常常干”，be used to doing 习惯于干，be used to do 被用来干。句子建议应用过去那种正确的方法做，并含有被动性。8.B。英语中习惯上避免重复，于是对方巧妙地用“我过去曾是”作答语。9.D。也可用usedn't there/usen't there 10.A。could,would常用于现在来表示委婉的语气，回答应用can 。11.C。“本应该”可用“be supposed+to+have+过去分词”，相当于should/ought to+have+过去分词 12.C。表过去有可能干某事：could have+过去分词。本句含有“当时有可能被当作讲本族语的人”13.D。从前句的语境lazy可以说本句含“本应该早已完成”之意。14.A。shall用于第三人称前可表征求意见、请求许可之意。15.A。used to 和would都可表示过去常常，但表示过去的习惯状态用used to。形成强烈的今昔对比用used to。若D答案用existed也对。16.D。在回答“情态动词+完成不定式”结构的句子时，答句里要在情态动词后加have.又如：“Could you have left your umbrella on the bus?”“Yes,I might have.”如果是被动语态，还要加上been。如：“Could he have been arrested by the police?”“Yes,he might have been.”17.D。umst,need,ought to在间接引语里可表示过去里。又如：They said that we must be back before supper.18.B。“had better +have+过去分词”可表“最好已干过”。19.C。can和be able to都可以表“能”，但表达特定场合经过努力能做到的事时用be able to。20.B。否定祈使句后的反意疑问句常用will。