知识详解
1 strength n． 力量，力气，体力；意志力；坚强；长处
(回归课本P32)The Chinese Central Weather Station can forecast a sandstorm some weeks before it arrives in Beijing，but the strength of the storm sometimes surprises people.
中央气象站能在沙尘暴到达北京前几个周进行预报，但风大得有时让人们吃惊。
归纳总结
例句探源
①I don’t have the strength to climb any further.
我没有力气再往上爬了。
②Diana pulled on the rope with all her strength.
黛安娜用尽全身的力气拉绳子。
③Repairs are necessary to strengthen the bridge.
这座桥需要维修加固。
④Be aware of your own strengths and weaknesses.
要意识到你自己的长处和短处。
易混辨析
strength，force，power，energy
(1)strength着重指人的体力或坚强的意志力。
(2)force指物理学意义上的“力”，也指为做某事而使用的力量，还可指武力。
(3)power指能力、权力、着重行动所根据的能力、本领或职权。
(4)energy主要指人的精力，或自然界中物理学定义中的“能，能量”。
①He pushed against the rock with all his strength.
②She’s always full of energy.
③The rioters were taken away by force.
④The party came to power_ at the last election.
即境活用
1．(高考湖北卷)To make members of a team perform better，the trainer first of all has to know their________and weaknesses.
A．strengths B．benefits
C．techniques D．values
解析：选A。句意“为了让一个队的成员表现更好，教练首先得知道他们的长处和不足。”
2.Filled with great________，the boy lifted the heavy bag onto his shoulder.
A．power B．energy
C．strength D．force
解析：选C。power表示“能力；权力”；energy表示“能量；能源；精力”；strength表示“力气”；force多指“武力，暴力”，举沉重的包应用“力气，力量”，所以选C。
2 concerned adj. 关心的；担心的；有关的(不用于名词前)
(回归课本P36)I can’t help but feel very concerned.
我禁不住感到很担心。
归纳总结
be concerned about/for关心；挂念
be concerned with与……有关；关心
concerned in牵涉到；与……有关
as/so far as...be concerned就……而言
concern n．担心(的事)
vt.使关心；使担忧；牵涉
concerning prep.关于
例句探源
①We were all concerned for/about his safety.
我们大家都担心他的安全。
②(朗文P409)Everyone concerned in the incident was questioned by the police.
所有与这起事件有关的人都受到了警方的盘问。
③As far as I’m concerned the whole idea is crazy.
在我看来，这一想法十分荒唐。
④(朗文P409)Businesses concerned with the oil industry do not support solar energy research.
与石油工业有关的企业都不支持太阳能的研究。
⑤There is growing concern about the effects of pollution on health.对于污染影响健康的关注越来越强烈。
⑥What concerns me is our lack of preparation for the change.
让我担心的是我们对事态的变化缺乏准备。
⑦We have several discussions concerning the matter.
关于这件事，我们已讨论了好几次。
即境活用
3．The comments which he made________marketing bothered his boss greatly.
A．being concerned
B．concerned
C．be concerned
D．concerning
解析：选D。which he made concerning marketing 是定语从句修饰先行词the comments，引导词在从句中作made的宾语，concerning是介词相当于about，表示“关于”。本句意为“他就营销所作的评论使老板深感不安。”
4.完成句子
You can tell your friend that you________________(关心)him but you have to go to school.
解析：be concerned about表示“关心，担心”。本句意为“你可以告诉你的朋友，你很关心他，但是你不得不去上学。”
答案：are concerned about
3 complain vt.& vi. 抱怨；发牢骚；投诉，控告
(回归课本P36)He does nothing but complain.
他只是不停地埋怨。
归纳总结
例句探源
①I’m going to complain to the manager about the quality of the MP4.
我打算向经理投诉MP4的质量问题。
②They complained that the price of books had increased.
他们抱怨书价上涨了。
③The patient is making a complaint to the doctor of his bad headache.
病人正在向医生诉说他的头痛。
即境活用
5.He ________to me about the bad weather he had while traveling there，from which I guessed that he must have had a very unpleasant journey there.
A．complained B．pretended
C．regretted D．complaint
解析：选A。complain to sb. about sth.“关于……向某人发牢骚”。complaint是名词。
6．完成句子
①Hence they could endure the hardship________________(毫无怨言地)。
解析：本句意为“因此他们能毫无怨言地忍受痛苦。”
答案：without complaint
②She________________________(抱怨)having been kept waiting for so long.
解析：本句意为“她抱怨让她等得太久了。”
答案：complains about/of
4 cut down 砍倒，杀死，减少，缩小(尺寸，数量)
(回归课本P31)Deserts are also created because people cut down trees and dig up grass.
由于人们砍伐树木，挖掘草地造成了土壤的沙化。
归纳总结
例句探源
①We are busy cutting trees down.
我们正在忙着砍树。
②We are doing all we can to cut down studying time and improve learning efficiency.
我们正在努力缩短学习时间并提高学习效率。
③The electricity company are threatening to cut us off.
电力公司以停电威胁我们。
④I wish Marie would stop cutting in on our conversation all the time.
我希望玛丽在我们谈话时别老插嘴。
⑤His mother has to cut up all his food for him.
他母亲不得不为他将所有的食物切碎。
即境活用
7．The new coat looks too large on Mary，so her mother had to ________.
A．cut it out B．cut it down
C．cut it off D．cut it up
解析：选A。句意：玛丽身上的新衣服太大，所以她妈妈将其进行剪裁。cut down砍倒，削减，缩小(尽寸等)；cut off剪掉，砍掉；cut up剪碎，剁碎，均不合题意。
8.I was________ in the middle of my call because I had no coins to put in the box.
A．cut off B．broken in
C．hung up D．put down
解析：选A。cut off中断，切断；break in闯入，打岔；hang up 挂断电话；put down放下，镇压。句意：在打电话期间我的电话被切断了，因为我没有硬币可投进电话机了。故A项符合。
5 be caught in 突然遭遇(风暴等)
(回归课本P32)“To have been caught in a sandstorm was a terrible experience，”he said.
他说：“遭遇上了沙尘暴是一次可怕的经历。”
归纳总结
catch v.抓住；患病；捕获；(被)卡住；搭上(汽车等)，当场发现，撞见,
catch sb.doing sth.抓到/看到某人正在做某事,catch up with赶上；追上,
catch one’s eye引起某人的注意,
catch hold of抓住
例句探源
①On the way home last night，they were caught in a storm.
昨天晚上在回家的路上，他们遭遇了暴风雨。
②(朗文P298)Steph’s hair got caught in the machine，and they had to cut it.
斯蒂夫的头发被机器夹住了，他们不得不把它剪断。
③(朗文P297)If you get caught stealing in some countries，they cut off your hand.
在有些国家，行窃被当场抓住的话是要被剁手的。
④At the moment our technology is more advanced，but other countries are catching up with us.
目前我们的技术比较先进，不过其他国家正在追赶上来。
即境活用
9．When I opened the door，a parcel on the floor________my eye.
A．met B．caught
C．drew D．attracted
解析：选B。考查固定短语catch one’s eye 表示“引起某人的注意”。本句意为“当我打开门时，地板上的一个包裹引起了我的注意”。
10.I still remember________chess in class by my teacher about twenty years ago.
A．to be caught to play
B．being caught playing
C．catching play
D．having caught playing
解析：选B。考查remember doing sth.表示“记得做过某事”以及be caught doing sth.表示“被抓到正在做某事”的用法。本句意为“我仍然记得大约二十年前在课堂上被老师抓到下象棋的情景”。
6 take in 吸收；理解；欺骗；包含；收留
(回归课本P35)Trees take in carbon dioxide and give out oxygen.
树吸收二氧化碳并放出氧气。
例句探源
①Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.
雨林对世界环境有巨大的影响，因为他们可以从阳光中吸收热量，调节气候。
②Our hotel is full；we can’t take in any more guests.
我们的旅馆已经客满，不能再接待客人了。
③This book is so difficult that I can’t take in what the author means.这本书很难，我无法理解作者的意思。
④(牛津在线)Don’t be taken in by his charming manner；he’s completely ruthless.
不要被他那副讨人喜欢的外表所迷惑，其实他冷酷无情。
即境活用
1．Don’t be________by products promising to make you lose weight quickly.
A．taken off B．taken out C．taken away D．taken in
解析：选D。句意是：不要被承诺迅速减肥的广告产品所欺骗。take off“起飞”；take out“取出来”；take away“带走”；take in“欺骗”。
7 look through 浏览，审核，彻底审查
(回归课本P40)Look through the reading passages and activities in this module.
浏览本单元的阅读文章和活动。
归纳总结
例句探源
①(牛津P1195)She looked through her notes before the exam.
考试前她匆匆看了一遍笔记。
②I’ve looked through all my papers but I still can’t find the contract.
我已把所有的文件检查了一遍，但还是没有找到那份合同。
即境活用
12．(高考湖北卷)Would you please________the paper for me and see if there are any obvious mistakes?
A．look around B．look into C．look up D．look through
解析：选D。句意是：你可不可以替我浏览一下这篇论文，看一看是否有明显的错误？此句要用look through表示“浏览”。look around“朝四周看”；look into“窥视；调查”；look up“查询”。
13.________magazines to find pictures that you can stick on your poster.
A．See through B．Look into C．Look through D．Pull through
解析：选C。句意为：翻阅杂志找找能贴在你的海报上的图片。look through“翻阅，浏览”；look into“调查”；pull through“从……中恢复健康”；see through“看穿，看透”，只有C项符合句意。
句型梳理
1【教材原句】 They are often so thick that you cannot see the sun，and the wind is sometimes strong enough to move sand dunes.(P32)
沙尘暴经常是非常混浊的以至于你看不见太阳，而且风有时大得能够刮动沙丘。
【句法分析】 so...that...“如此……以至于……”，引导结果状语从句。
so...that和such...that引导的结果状语从句都表示主句的动作或状态达到一定程度而引起的结果。so是副词，用来修饰形容词、副词、分词或其他结构；such 是形容词，用来修饰名词或名词短语。such 修饰单数可数名词且名词前有形容词时，可用so替换such，冠词与形容词交换位置，构成“so＋adj.＋a(an)＋名词”。名词前有many，much，few等表示数量的词时，一般用“so...that...”句型。
so...that...和such...that...构成以下句型：
但little意为“小的”时，只能用such。为加强语气，“so(such)．..that”结构中的so或such位于句首时，主句要用部分倒装语序。例如：
①He spoke in so low a voice that none of the people in the hall heard what he was saying.
他讲话的声音那么小，以至于大厅里的人都没听清他在讲什么。
②It is such fine weather that we all want to go to the park.
今天天气很好，我们都想去公园。
③He earned so little money that he couldn’t support his family.
他挣的钱很少，以至于不能养家糊口。
④So fast did he walk that none of us was his equal.
他走得如此之快以致没人能跟上他。
⑤It is so quiet in the room that you can hear the drop of a pin.
房间里静得连(地上)掉根针都能听见。
即境活用
14．My suitcase became damaged on the journey home，________the lid would not stay closed.
A．so that B．in order that C．because D．now that
解析：选A。so that引导一个结果状语从句，表示“结果盖子扣不死了”。
15.He is________a careless boy that he has made________many mistakes in the final exams.
A．such；such B．so；such C．so；so D．such；so
解析：选D。本题考查such和so两个词的用法。第一空考查的是such＋a＋adj.＋可数名词单数＋that从句，意思是“如此……以至于”；第二空考查的是so＋many/few＋可数名词，意思是“如此多/少的……”。故选D。
2【教材原句】 The garbage is then taken away and, if possible，recycled.(P39)
然后垃圾被带走，如果可能的话会进行回收利用。
【句法分析】 (1)if possible是if it is possible的省略形式。当if，when, while，until，unless，once，whether等引导的状语从句的主语与主句的主语相同，并且从句中含有系动词be的某种形式时，或从句的主语是it且含有be动词时，从句中的主语及部分谓语(be动词)可省略。
(2)if引导省略的情况有下列几种：
if any如果有的话
if necessary如果需要的话
if so如果是这样的话
if ever如果曾经有的话
if not 如果不这样的话
①Unless necessary，you’d better not refer to the dictionary.
你最好别查字典，除非有必要。
②I want to avoid the rush hour traffic if possible.
如果可能的话，我想避开交通高峰期。
③I think there’s a train at midday.If not you’ll have to wait till 12∶30.
我想正午会有一班火车。要是没有，你只好等到12点半了。
④Brian rarely, if ever，gets to bed before 3 a．m..
布赖恩难得在凌晨3点钟以前上床睡觉。
⑤I don’t suppose there will be more than a dozen left，if any.
我认为即使还有的话也不会超过十二个。
即境活用
16．(高考大纲全国卷Ⅱ)Though________to see us，the professor gave us a warm welcome.
A．surprising B．was surprised C．surprised D．being surprised
解析：选C。句意：尽管见到我们很惊讶，教授还是热情地欢迎了我们。though 引导让步状语从句，后省略了he was。surprised多指“人对某事感到惊讶”，故选C。
17.?Have you got any particular plans for the coming holiday?
?Yes.________，I’m going to visit some homes for the old in the city.
A．If ever B．If busy C．If anything D．If possible
1 strength n． 力量，力气，体力；意志力；坚强；长处
(回归课本P32)The Chinese Central Weather Station can forecast a sandstorm some weeks before it arrives in Beijing，but the strength of the storm sometimes surprises people.
中央气象站能在沙尘暴到达北京前几个周进行预报，但风大得有时让人们吃惊。
归纳总结
例句探源
①I don’t have the strength to climb any further.
我没有力气再往上爬了。
②Diana pulled on the rope with all her strength.
黛安娜用尽全身的力气拉绳子。
③Repairs are necessary to strengthen the bridge.
这座桥需要维修加固。
④Be aware of your own strengths and weaknesses.
要意识到你自己的长处和短处。
易混辨析
strength，force，power，energy
(1)strength着重指人的体力或坚强的意志力。
(2)force指物理学意义上的“力”，也指为做某事而使用的力量，还可指武力。
(3)power指能力、权力、着重行动所根据的能力、本领或职权。
(4)energy主要指人的精力，或自然界中物理学定义中的“能，能量”。
①He pushed against the rock with all his strength.
②She’s always full of energy.
③The rioters were taken away by force.
④The party came to power_ at the last election.
即境活用
1．(高考湖北卷)To make members of a team perform better，the trainer first of all has to know their________and weaknesses.
A．strengths B．benefits
C．techniques D．values
解析：选A。句意“为了让一个队的成员表现更好，教练首先得知道他们的长处和不足。”
2.Filled with great________，the boy lifted the heavy bag onto his shoulder.
A．power B．energy
C．strength D．force
解析：选C。power表示“能力；权力”；energy表示“能量；能源；精力”；strength表示“力气”；force多指“武力，暴力”，举沉重的包应用“力气，力量”，所以选C。
2 concerned adj. 关心的；担心的；有关的(不用于名词前)
(回归课本P36)I can’t help but feel very concerned.
我禁不住感到很担心。
归纳总结
be concerned about/for关心；挂念
be concerned with与……有关；关心
concerned in牵涉到；与……有关
as/so far as...be concerned就……而言
concern n．担心(的事)
vt.使关心；使担忧；牵涉
concerning prep.关于
例句探源
①We were all concerned for/about his safety.
我们大家都担心他的安全。
②(朗文P409)Everyone concerned in the incident was questioned by the police.
所有与这起事件有关的人都受到了警方的盘问。
③As far as I’m concerned the whole idea is crazy.
在我看来，这一想法十分荒唐。
④(朗文P409)Businesses concerned with the oil industry do not support solar energy research.
与石油工业有关的企业都不支持太阳能的研究。
⑤There is growing concern about the effects of pollution on health.对于污染影响健康的关注越来越强烈。
⑥What concerns me is our lack of preparation for the change.
让我担心的是我们对事态的变化缺乏准备。
⑦We have several discussions concerning the matter.
关于这件事，我们已讨论了好几次。
即境活用
3．The comments which he made________marketing bothered his boss greatly.
A．being concerned
B．concerned
C．be concerned
D．concerning
解析：选D。which he made concerning marketing 是定语从句修饰先行词the comments，引导词在从句中作made的宾语，concerning是介词相当于about，表示“关于”。本句意为“他就营销所作的评论使老板深感不安。”
4.完成句子
You can tell your friend that you________________(关心)him but you have to go to school.
解析：be concerned about表示“关心，担心”。本句意为“你可以告诉你的朋友，你很关心他，但是你不得不去上学。”
答案：are concerned about
3 complain vt.& vi. 抱怨；发牢骚；投诉，控告
(回归课本P36)He does nothing but complain.
他只是不停地埋怨。
归纳总结
例句探源
①I’m going to complain to the manager about the quality of the MP4.
我打算向经理投诉MP4的质量问题。
②They complained that the price of books had increased.
他们抱怨书价上涨了。
③The patient is making a complaint to the doctor of his bad headache.
病人正在向医生诉说他的头痛。
即境活用
5.He ________to me about the bad weather he had while traveling there，from which I guessed that he must have had a very unpleasant journey there.
A．complained B．pretended
C．regretted D．complaint
解析：选A。complain to sb. about sth.“关于……向某人发牢骚”。complaint是名词。
6．完成句子
①Hence they could endure the hardship________________(毫无怨言地)。
解析：本句意为“因此他们能毫无怨言地忍受痛苦。”
答案：without complaint
②She________________________(抱怨)having been kept waiting for so long.
解析：本句意为“她抱怨让她等得太久了。”
答案：complains about/of
4 cut down 砍倒，杀死，减少，缩小(尺寸，数量)
(回归课本P31)Deserts are also created because people cut down trees and dig up grass.
由于人们砍伐树木，挖掘草地造成了土壤的沙化。
归纳总结
例句探源
①We are busy cutting trees down.
我们正在忙着砍树。
②We are doing all we can to cut down studying time and improve learning efficiency.
我们正在努力缩短学习时间并提高学习效率。
③The electricity company are threatening to cut us off.
电力公司以停电威胁我们。
④I wish Marie would stop cutting in on our conversation all the time.
我希望玛丽在我们谈话时别老插嘴。
⑤His mother has to cut up all his food for him.
他母亲不得不为他将所有的食物切碎。
即境活用
7．The new coat looks too large on Mary，so her mother had to ________.
A．cut it out B．cut it down
C．cut it off D．cut it up
解析：选A。句意：玛丽身上的新衣服太大，所以她妈妈将其进行剪裁。cut down砍倒，削减，缩小(尽寸等)；cut off剪掉，砍掉；cut up剪碎，剁碎，均不合题意。
8.I was________ in the middle of my call because I had no coins to put in the box.
A．cut off B．broken in
C．hung up D．put down
解析：选A。cut off中断，切断；break in闯入，打岔；hang up 挂断电话；put down放下，镇压。句意：在打电话期间我的电话被切断了，因为我没有硬币可投进电话机了。故A项符合。
5 be caught in 突然遭遇(风暴等)
(回归课本P32)“To have been caught in a sandstorm was a terrible experience，”he said.
他说：“遭遇上了沙尘暴是一次可怕的经历。”
归纳总结
catch v.抓住；患病；捕获；(被)卡住；搭上(汽车等)，当场发现，撞见,
catch sb.doing sth.抓到/看到某人正在做某事,catch up with赶上；追上,
catch one’s eye引起某人的注意,
catch hold of抓住
例句探源
①On the way home last night，they were caught in a storm.
昨天晚上在回家的路上，他们遭遇了暴风雨。
②(朗文P298)Steph’s hair got caught in the machine，and they had to cut it.
斯蒂夫的头发被机器夹住了，他们不得不把它剪断。
③(朗文P297)If you get caught stealing in some countries，they cut off your hand.
在有些国家，行窃被当场抓住的话是要被剁手的。
④At the moment our technology is more advanced，but other countries are catching up with us.
目前我们的技术比较先进，不过其他国家正在追赶上来。
即境活用
9．When I opened the door，a parcel on the floor________my eye.
A．met B．caught
C．drew D．attracted
解析：选B。考查固定短语catch one’s eye 表示“引起某人的注意”。本句意为“当我打开门时，地板上的一个包裹引起了我的注意”。
10.I still remember________chess in class by my teacher about twenty years ago.
A．to be caught to play
B．being caught playing
C．catching play
D．having caught playing
解析：选B。考查remember doing sth.表示“记得做过某事”以及be caught doing sth.表示“被抓到正在做某事”的用法。本句意为“我仍然记得大约二十年前在课堂上被老师抓到下象棋的情景”。
6 take in 吸收；理解；欺骗；包含；收留
(回归课本P35)Trees take in carbon dioxide and give out oxygen.
树吸收二氧化碳并放出氧气。
例句探源
①Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.
雨林对世界环境有巨大的影响，因为他们可以从阳光中吸收热量，调节气候。
②Our hotel is full；we can’t take in any more guests.
我们的旅馆已经客满，不能再接待客人了。
③This book is so difficult that I can’t take in what the author means.这本书很难，我无法理解作者的意思。
④(牛津在线)Don’t be taken in by his charming manner；he’s completely ruthless.
不要被他那副讨人喜欢的外表所迷惑，其实他冷酷无情。
即境活用
1．Don’t be________by products promising to make you lose weight quickly.
A．taken off B．taken out C．taken away D．taken in
解析：选D。句意是：不要被承诺迅速减肥的广告产品所欺骗。take off“起飞”；take out“取出来”；take away“带走”；take in“欺骗”。
7 look through 浏览，审核，彻底审查
(回归课本P40)Look through the reading passages and activities in this module.
浏览本单元的阅读文章和活动。
归纳总结
例句探源
①(牛津P1195)She looked through her notes before the exam.
考试前她匆匆看了一遍笔记。
②I’ve looked through all my papers but I still can’t find the contract.
我已把所有的文件检查了一遍，但还是没有找到那份合同。
即境活用
12．(高考湖北卷)Would you please________the paper for me and see if there are any obvious mistakes?
A．look around B．look into C．look up D．look through
解析：选D。句意是：你可不可以替我浏览一下这篇论文，看一看是否有明显的错误？此句要用look through表示“浏览”。look around“朝四周看”；look into“窥视；调查”；look up“查询”。
13.________magazines to find pictures that you can stick on your poster.
A．See through B．Look into C．Look through D．Pull through
解析：选C。句意为：翻阅杂志找找能贴在你的海报上的图片。look through“翻阅，浏览”；look into“调查”；pull through“从……中恢复健康”；see through“看穿，看透”，只有C项符合句意。
句型梳理
1【教材原句】 They are often so thick that you cannot see the sun，and the wind is sometimes strong enough to move sand dunes.(P32)
沙尘暴经常是非常混浊的以至于你看不见太阳，而且风有时大得能够刮动沙丘。
【句法分析】 so...that...“如此……以至于……”，引导结果状语从句。
so...that和such...that引导的结果状语从句都表示主句的动作或状态达到一定程度而引起的结果。so是副词，用来修饰形容词、副词、分词或其他结构；such 是形容词，用来修饰名词或名词短语。such 修饰单数可数名词且名词前有形容词时，可用so替换such，冠词与形容词交换位置，构成“so＋adj.＋a(an)＋名词”。名词前有many，much，few等表示数量的词时，一般用“so...that...”句型。
so...that...和such...that...构成以下句型：
但little意为“小的”时，只能用such。为加强语气，“so(such)．..that”结构中的so或such位于句首时，主句要用部分倒装语序。例如：
①He spoke in so low a voice that none of the people in the hall heard what he was saying.
他讲话的声音那么小，以至于大厅里的人都没听清他在讲什么。
②It is such fine weather that we all want to go to the park.
今天天气很好，我们都想去公园。
③He earned so little money that he couldn’t support his family.
他挣的钱很少，以至于不能养家糊口。
④So fast did he walk that none of us was his equal.
他走得如此之快以致没人能跟上他。
⑤It is so quiet in the room that you can hear the drop of a pin.
房间里静得连(地上)掉根针都能听见。
即境活用
14．My suitcase became damaged on the journey home，________the lid would not stay closed.
A．so that B．in order that C．because D．now that
解析：选A。so that引导一个结果状语从句，表示“结果盖子扣不死了”。
15.He is________a careless boy that he has made________many mistakes in the final exams.
A．such；such B．so；such C．so；so D．such；so
解析：选D。本题考查such和so两个词的用法。第一空考查的是such＋a＋adj.＋可数名词单数＋that从句，意思是“如此……以至于”；第二空考查的是so＋many/few＋可数名词，意思是“如此多/少的……”。故选D。
2【教材原句】 The garbage is then taken away and, if possible，recycled.(P39)
然后垃圾被带走，如果可能的话会进行回收利用。
【句法分析】 (1)if possible是if it is possible的省略形式。当if，when, while，until，unless，once，whether等引导的状语从句的主语与主句的主语相同，并且从句中含有系动词be的某种形式时，或从句的主语是it且含有be动词时，从句中的主语及部分谓语(be动词)可省略。
(2)if引导省略的情况有下列几种：
if any如果有的话
if necessary如果需要的话
if so如果是这样的话
if ever如果曾经有的话
if not 如果不这样的话
①Unless necessary，you’d better not refer to the dictionary.
你最好别查字典，除非有必要。
②I want to avoid the rush hour traffic if possible.
如果可能的话，我想避开交通高峰期。
③I think there’s a train at midday.If not you’ll have to wait till 12∶30.
我想正午会有一班火车。要是没有，你只好等到12点半了。
④Brian rarely, if ever，gets to bed before 3 a．m..
布赖恩难得在凌晨3点钟以前上床睡觉。
⑤I don’t suppose there will be more than a dozen left，if any.
我认为即使还有的话也不会超过十二个。
即境活用
16．(高考大纲全国卷Ⅱ)Though________to see us，the professor gave us a warm welcome.
A．surprising B．was surprised C．surprised D．being surprised
解析：选C。句意：尽管见到我们很惊讶，教授还是热情地欢迎了我们。though 引导让步状语从句，后省略了he was。surprised多指“人对某事感到惊讶”，故选C。
17.?Have you got any particular plans for the coming holiday?
?Yes.________，I’m going to visit some homes for the old in the city.
A．If ever B．If busy C．If anything D．If possible
