高中英语必修课----B4 Unit 2 Working the land语言点知识讲解及巩固练习题

高中英语必修课----B4Unit2Working the land语言点知识讲解及巩固
练习题（含答案解析）
目标认知
重点词汇
struggle，expand，check，enough，compare，provide，confuse，damage，affect，reduce，method，avoid，every
重点短语
thanks to，rid sb./sth.of sb./sth.，care about，would rather，too much，lead to，build up，in addition，turn to，focus on，keep...free from
重点句型
so that可以引导目的状语从句
even though
have been doing
as用法小结
知识讲解
重点词汇
【高清课堂：词汇精讲】
struggle
重点例句：
Indeed,his sun burnt face and arms and his slim,strong body are just like those of millions of Chinese farmers,for whom he has struggled for the past five decades.
struggle(vi.&n.)
(1)fight(with sb.)
（与某人）争斗,搏斗,打斗
(2)move one's body vigorously,trying to get free
挣扎
(3)try to overcome difficulties
拼搏；努力；
struggle against/with
struggle for/to do sth.
with a struggle
without a struggle
struggle to one's feet
struggle through the snowstorm
a life and death struggle
expand
重点例句：
Dr.Yuan searched for a way to increase rice harvests without expanding the area of the fields.
expand(vt.&vi.)
(1)become greater in size,number or importance
变大;扩大;增强
Metals expand when they are heated.
Why not try to expand your story into a novel?
(2)spread out
伸展
The petals of the flowers expanded in the sunshine.
expand(vt.&vi.)
(1)become greater in size,number or importance
变大;扩大;增强
Metals expand when they are heated.
Why not try to expand your story into a novel?
(2)spread out
伸展
The petals of the flowers expanded in the sunshine.
易混辨析
stretch,spread,extend，expand
这几个词的共同意思是“扩展”。

(1)stretch指把有弹性的物体拉长或拉宽。

(2)spread意思较为广泛：
①把某物体展开，铺平。

②把许多物体铺撒在一定的面积上。

③指某事物在人与人之间传播，越传越广。

(3)extend指在空间或时间上延伸，一般有一个
大致的延伸方向。

(4)expand本义指在面积、体积上的扩大，
一般是从中心向四周扩大。

用作比喻义时
可以指各种事物的增长、扩大等。

check
【原句回放】Then skim the passage to check if you were right．然后浏览短文。

检查一下你是否正确。

(P9)
【点拨】check vt．检查；核对；制止；阻挡；寄存；托运
Will you please check these figures？
你把这些数字核对一下好吗？
Doctors are trying to check the spread of the disease with drugs．医生正试图用药物阻止这种疾病的蔓延。

They have checked the enemy’s advance．
他们已阻挡住敌人的攻势。

He checked his coat as he went in．
他进去时把外衣寄存起来。

【拓展】
check in(旅馆、飞机等)登记；报到
check up调查
易混辨析
check与examine的区别
①examine表示为了解某种情况而仔细“检查”、“审查”。

Yesterday the firemen examined the ground carefully，but were not able to find any broken glass．
昨天，消防队员们仔细地检查了地面，但未能找到任何碎玻璃。

My suitcases were examined at the Customs when I entered the country．入境时，我的提包在海关受到了检查。

②check表示“检查”、“核对”，以查明是否正确。

How does his story check out with the facts？
他的说法经核实过后真实程度有多大？
Please check over the speech draft and correct the mistakes，if any．请把讲演稿检查一遍，如果有错误，请改正过来。

enough
【原句回放】One dream is not always enough，especially for a person who loves and cares for his people。

一个梦想总是不够的。

特别是对于一个热爱和关心人民的人来说更是如此。

(P10)【点拨】enough作副词时，充当形容词或副词的修饰词，但必须后置。

作代词时，既可以代表可数名词，也可以代表不可数名词。

作形容词时，可修饰可数名词或不可数名词，可放在被修饰的名词前，也可以放在后面。

He walks slowly enough．他走得够慢了。

If enough of you are interested，we’ll organize a trip to the theatre．
如果你们中有足够多的人感兴趣，我们就组织去看一场戏。

I have enough time(time enough)to finish the work．
我有足够的时间来完成这项工作。

【拓展】
adj./adv.+enough+to do
在本结构中，enough是程度副词，修饰形容词或副词，不定式作结果状语。

本结构的意思是“足够……以至于能做某事”，其否定形式为not enough...to do sth.，不定式的逻辑主语为句子的主语。

He runs fast enough to catch a bus．
他跑得非常快，能追上公共汽车。

He is old enough to go to school now．
他现在年龄够大了，可以去上学了。

温馨提示
在enough to do结构中，不定式的逻辑主语与句子主语一致。

如果主语不一致，则用so...that 结构。

His progress in English study was so great that he could read English newspapers six months later．他在英语学习方面取得的进步如此大，以至于六个月后他就能够读英语报纸了。

The horse ran so fast that none of us could catch up with it．
那匹马跑得太快了，我们没有人能追得上它。

compare
【原句回放】Write out your idea and then compare it with your partner．写下你的观点，然后与你的同伴进行比较。

(P11)
【点拨】compare vt.＆vi.作“比较，对照”讲时，常与介词with连用；作“比作”讲时，多和介词to连用。

If you compare this book with that one，you will find this one much more interesting．如果你把这本书和那本比较一下，你就会发现这本书有趣多了。

Please compare your translation with the model translation on the blackboard．请把你的翻译和黑板上的范文比较一下。

Young people are compared to the sun in the morning．
人们把年轻人比作早晨的太阳。

Two concert hails that just do not compare．
无法比较的两个音乐厅。

【拓展】
compared with(to)为过去分词短语，通常在句中用作状语，表示“和……比起来”，这时介词with和to都可使用。

Compared to/with many people，she was indeed very fortunate．
和许多人比起来，她确实很幸运。

It was a small place then compared to/with it is now．
和现在比起来，那时它还是一个小地方。

The hardship is nothing compared to/with that the Red Army faced on the Long March．
和红军长征时受的苦比起来，这点苦算不了什么
1．would prefer to宁愿(P12)
prefer vt.意为“更喜欢”，后接名词、代词、不定式、动名词作宾语。

在没有明确指出比较对象时，用不定式、动名词意义大致相同。

—Which would you prefer，coffee or tea？咖啡和茶，你更喜欢哪一种?
—I prefer tea．我更喜欢茶。

People in the south prefer rice while those in the north prefer food made from flour．南方人爱吃米饭，而北方人较喜欢吃面食。

He chose Spain，but personally I'd prefer to go to Greece．
他选了西班牙，但就我个人而言，我倒想去希腊。

【拓展】(1)在词组prefer...to...中，to是介词，其作用是引出两个比较对象，因此，动词prefer 的宾语和介词to的宾语在形式上应一致，可以是名词、代词或动名词，不可用不定式。

He said he preferred the country to the city．
他说城市和农村相比，他更喜欢农村。

She prefers dancing to singing．
跳舞和唱歌相比，她更喜欢跳舞。

(2)在prefer...rather than...的结构中，要用“prefer to do...rather than do...”，意为“宁愿做……而不做……”。

The soldier preferred to die rather than give in before the enemy．这位战士宁愿死，也不在敌人面前屈服。

(3)prefer还可接that引导的宾语从句，相当于hope的用法；也可接复合宾语，即“prefer
sb．to do…”，意为“更希望某人干……”。

I’d prefer you not to go there alone．
我更希望你不要单独去那儿。

We prefer that they(should)do it in a different way．
我们更希望他们用一种不同的方法去做。

温馨提示
prefer的过去式、过去分词和现在分词要双写字母r，然后加-ed或-ing．
provide
【原句回放】to provide with things necessary for a certain purpose为了特殊目的而提供必需的东西(P12)
【点拨】provide vt.提供；供应；供给
The company offered to provide anything we needed most．
这家公司主动提出向我们提供我们最需要的任何东西。

The firm has provided the manager with a new car．
这家公司已经向这位经理提供了一辆新的汽车。

【拓展】provide sth.for sb./provide sb.with sth.给某人提供某物
provide against sth.防备发生某事；预防某事
provide for sb.供应某人所需
provide for sth.为某事的发生做准备
confuse
【原句回放】It is important to explain this again or we will confuse the students．把这再解释一遍是很重要的，否则的话我们就会使学生们犯糊涂。

(P13)
【点拨】confuse vt.使糊涂，使迷惑；混淆，混同；使更难于理解
They confused the teacher by having the same names．
他们同名同姓，这把老师搞糊涂了。

Her unexpected arrival confused all our plans．
她的突然到来把我们所有的计划都打乱了。

I always confuse the twin sisters．They look so alike．
我总是分不出这对孪生姐妹，她们看上去简直一模一样。

【拓展】
confused adj.糊涂的，迷乱的
confusedly adv.迷乱地，糊涂地
confusing adj.莫名其妙的，难以理解的
confusion n.迷乱，迷惑
damage
【原句回放】First，they damage the land by killing the helpful bacteria and pests as well as the harmful ones．首先，化肥在杀死病菌和害虫的同时也会杀死有益的细菌和昆虫，从而破坏土地。

(P14)
【点拨】damage n.损失；损害，损坏；(前面与the连用)价钱；(pl)赔偿费；vt.损害，损坏；使受损失
The storm did a lot of damage to the crops．
暴风雨使庄稼受到了很大损失。

What are the damage for the wash job of my car?
清洗我的车要多少钱?
The court awarded￡500in damages to the injured．
法庭判给受伤者500英镑的赔偿费。

The earthquake damaged several buildings．
地震使一些建筑受到了破坏。

温馨提示
damage作“损坏”讲一般用作不可数名词。

易混辨析
damage，destroy与ruin的区别
①damage指“损坏”，一般暗示损坏后价值或效益会降低，这种损坏是部分性的，有时该词也用于借喻。

Her head was slightly damaged as a result of her long illness．
长期生病使她的心脏受到轻度损伤。

What they said and did damaged the relations between the two countries．他们的言行损害了这两个国家之间的关系。

②destroy意为“破坏；摧毁；消灭；毁灭”，指完全彻底地破坏，含有无法修复之意，也可用于借喻。

The building was completely destroyed by the fire．
这座房子被大火烧光了。

The Nazi wanted to destroy people’s hopes，but in the end what was destroyed was the Nazi’s dream by the power of people．纳粹想摧毁人民的希望，但最终是纳粹的梦想被人民的力量所摧毁。

③ruin可以表达“毁坏”，也可以用于引申意义。

He ruined his prospects by carelessness．
他因疏忽大意而断送了前途。

The rain will ruin the crops．这雨会把庄稼毁掉的。

It poured with rain and my dress was ruined．
大雨倾盆，我的连衣裙已淋得不成样子了。

(2)as well as
①用于比较，表示“和……一样好”。

He plays football as well as，if not better than，that man．
他足球踢得要是不比那人好，起码是一样好。

②连词词组，表示“同，还有，不但……而且”。

Einstein was a violinist as well as a physicist．
爱因斯坦不仅是物理学家，而且还是一位小提琴手。

We shall travel by night as well as by day．
我们不仅白天旅行而且晚上也旅行。

The manager as well as the workers wishes for an outing．
经理和他的工人们都希望去远足。

温馨提示
①as well as连接两个名词或代词作主语时，后面部分可视为插入语，因此，谓语动词应和前一名词或代词保持人称和数的一致。

上句还可译为：
The manager，as well as workers，wishes for an outing．
The manager wishes for an outing as well as the worker．
The workers wish for an outing and the manager wishes as well．
②as well as连接两个动词时，后面的动词用-ing形式。

He hurt his arm as well as breaking his leg．
他伤了胳膊，又弄断了腿。

易混辨析
as well as与not only...but also的区别
as well as强调前一部分；谓语动词和前面的主语一致。

Lily as well as her parents is very fond of classical music．
不但莉莉的父母，而且连莉莉也喜欢古典音乐。

②not only...but also...强调后一部分；谓语动词的单复数要和后面的主语一致。

Not only the students but also the teacher was invited．
不仅学生们被邀请，而且那位教师也被邀请了。

affect
【原句回放】This affects crops and therefore，animals and humans，since chemicals get inside the crops and cannot just be washed off．这会影响到庄稼，进而影响到动物和人类，因为化学成分会进入到农作物中。

并且不能被冲洗掉。

(P14)
【点拨】affect vt.作“影响”解，通常指对身体、思想或情绪等带来不良影响。

有“感动”、“触动”之意，相当于move。

有“感染”、“侵袭”之意，一般指感染疾病。

The rise in prices will affect all classes．
物价的上涨将会使各阶层的人都受到影响。

Some plants are quickly affected by cold．
有些植物很快就受到了寒冷的影响。

I was too much affected to answer．我感动得回答不出话来。

This disease affects millions of people in the world every year．
这种疾病每年都使全世界数百万人受到感染。

易混辨析
affect，effect与influence的区别
(1)affect指“产生的影响之大足以引起反应”，着重“影响”的动作，有时含有“对……产
生不利影响”的意思。

This article will affect my thinking．这篇文章将会影响我的思想。

(2)effect指“实现”、“达成”，着重“造成”一种特殊的效果。

This book effected a change in my opinion．
这本书使我的看法起了变化。

(3)influence指“通过说服、举例等对行动、思想、性格等产生不易觉察到的，潜移默化的影响”。

Influenced by a high-school biology teacher，he took up the study of medicine．在一位中学生物教师的影响下，他从事医学研究。

reduce
【原句回放】A healthy soil reduces disease and helps crops grow strong and healthy．健康的土壤会减少病虫害并且帮助农作物茁壮成长。

(P14)
【点拨】reduce vt.＆vi.减少，缩小(尺寸、数量、价格等)；使陷入(更坏的)境地，使沦落
The great fire reduced the forest to a few trees．
大火将森林烧得只剩下几棵树。

The price has been reduced to$5．
价格已经降到了5美元。

Enemy’s bombers reduced the city to rubble．
敌人的轰炸机把城市夷为了平地。

The Depression reduced many。

people to begging on street cornets．
大萧条使许多人沦落到街头乞讨。

The store has drastically reduced winter coats．
商店对冬装大减价。

【拓展】
reduce...to...(把……)减少到……
reduce...by...(把……)减少了……
reduce sth.to...使……变为(某个状态)
reduce sb.to(doing)sth.迫使某人陷入(不佳状态)；
使某人不得不……
method
【原句回放】These many different organic farming methods have the same goal：to grow good food and avoid damaging the environment or people’s health．这些不同的有机耕作的方法有着同样的目标：种植好的粮食，避免损害环境或者人们的健康。

(P14)
【点拨】method n．(系统的、逻辑的)方法、办法；秩序；条理；规律
Try the new method．and maybe you’ll succeed．
试试这种新方法，或许你会成功。

We must get some method into our office filling．
我们必须把公文归档工作弄出些条理来。

【拓展】
with methods of用……方法
with this/that method用这/那种方法
in this/that way用这种/那种方法
in the same way用相同的方法
in different ways用不同的方法
by this/these means用这种/这些方法
易混辨析
way，method与means的区别
①way为可数名词，后接不定式或of+动名词。

We must find a way to solve this kind of problem．
我们必须找到解决这种问题的方法。

I’m not happy with this way of working．
我不喜欢这种工作方式。

②method也是可数名词，常指系统的、逻辑的方法、办法，后接of+动名词，不接不定式。

He is a man of accuracy and strict method．
他是个精细而严谨的人。

③means单复数形式相同，其前有a，one，this，that，every等时表单数意义，其前有such，these，those，all等时表复数意义，其多指抽象或概括性的意思，也可以指(交通等)手段，后可接不定式，也可接of+动名词／名词。

There is no means of finding out what happened．
无法搞清楚发生了什么事情。

avoid
【原句回放】These many different organic farming methods have the same goal：to grow good food and avoid damaging the environment or people’s health．这些不同的有机耕作的方法有着同样的目标：种植好的粮食，避免损害环境或者人们的健康。

(P14)
avoid vt．避开；避免；逃避
后面跟动词时，用其v.-ing形式。

I crossed the street to avoid meeting him，but he saw me and came running towards me．
我横穿马路以便避开他，但他看到了我并朝我跑过来。

To avoid confusion，the teams wore different colours．
为避免混淆，两队分穿不同颜色的衣服。

Are you trying to avoid me?你是不是想避开我?
【拓展】
avoidable adj.可避免的avoidably adv.可避免地
avoidless adj.无法避免的
every
【原句回放】They often change the kind of crop in each field every few years，for example，growing corn or wheat and then the next year peas or soybeans．在同一块地里，他们经常每隔几年就换种农作物。

例如，种玉米或小麦后来年再改种豌豆或大豆。

(P14)
【点拨】every表“每……”时，用法如下：
every+基数词+复数名词；every+序数词+单数可数名词；every+other+单数可数名词；every +few+复数名词
I go there every two weeks．
我每两周(每隔一周)去那儿一次。

They move on to a new place every two or three years．
他们每两到三年就搬到一个新地方。

He comes to see his parents every third week．
他每三周就来看他的父母一次。

Every fourth day he goes to have a swim．
每四天他就去游一次泳。

He goes to town every other day(every two days=every second day)．他每两天(每隔一天)就去镇上一次。

温馨提示
①every表“每(每隔)”时，上述句型中every均不可换成each。

②every指时间时，对every...短语提问用how often。

He goes to that school to see his old teacher every other week．
How often does he go to that school to see his old teacher?
③every后可接few，但不能接a few，因为every一词已包含了a之意，另外every后也不能接some，several，many等词。

every后接序数词时，则修饰单数可数名词。

重点短语
thanks to
【原句回放】Thanks to his research，the UN has more tools in the battle to rid the world
of hunger．由于他的研究。

联合国在消除世界饥饿的战斗中有了更多的方法。

(P10)
【点拨】thanks to是固定表达，在句中作原因状语。

(1)thanks to sb./sth.:because of sb./sth.幸亏；由于，因为
Thanks to your help，we were successful．
由于你的帮助，我们成功了。

Thanks to his help，we finished our work on time．
幸亏有他的帮助，我们按时完成了工作。

Thanks to his timely help，the little boy was saved．
多亏了他及时的帮助，这个小男孩得救了。

归纳拓展
表示“原因”的介词短语有：
because of因为，由于due to由于，因为owing to由于，归功于on account of由于as a result of由于in that因为(由于)……
温馨提示
due to(sb./sth.)引导的原因状语一般不放在句首。

The project had to be abandoned due to a lack of government funding．这项工程由于缺乏政府的资助而不得不放弃。

rid sb./sth.of sb./sth.
【原句回放】Thanks to his research，the UN has more tools in the battle to rid the world of hunger．由于他的研究。

联合国在消除世界饥饿的战斗中有了更多的方法。

(P10)
【点拨】rid sb./sth.of sb./sth.除掉；去除
Further measures will be taken to rid our streets of crime．
将进一步采取措施来防止街头犯罪。

【拓展】
get rid of摆脱，扔掉
be rid of摆脱
break away from摆脱，脱离
I can’t get rid of this headache．
我不能摆脱头痛之苦。

I was glad to be rid of the car when I finally sold it．
把车卖掉时，我很庆幸终于脱手了。

The robbery suspect broke away from the prison．
抢劫嫌疑犯从监狱逃脱了。

care about
【原句回放】However，he doesn’t care about being famous．但是，他对成名并不在意。

(P10)【点拨】care about忧虑；关心；惦念
People all over the word are caring about the future of Iraq．
全世界的人们都在关心伊拉克的前途。

All she cares about is her social activities．
她所关心的是她的社交活动。

They don’t care(about)what will happen to the family．
他们对于这个家庭将要发生的事情漠不关心。

【拓展】care for喜爱；照顾；重视
take care当心
take care of照料；关怀；处理
take into care(把没人管教的孩子)送进教养院
under the care of由……管理；在……的照料下；在……的保护下
with care小心；慎重
would rather或had rather
【原句回放】He would much rather keep time for his hobbies．他宁愿把时间花在自己的业余爱好上。

(P10)
【点拨】would rather或had rather的意思是“宁肯”、“宁愿”，后跟动词原形，其否定形式为would rather(had rather)not do sth．
I would rather stay at home(than go out)．
我宁愿待在家里(也不愿出去)。

温馨提示
would rather后面可以跟从句，运用虚拟语气，即：表达与现在事实相反，运用一般过去时；
与过去事实相反，运用过去完成时。

I would rather my daughter attended a public school．
我希望我的女儿能上公立学校。

【拓展】
表达“宁可做某事，也不愿做某事”有如下表达法：
①would rather do sth.than do sth.
I would rather die than give in．我宁可死也不投降。

②would do sth.rather than do sth.
I would do it myself rather than advise him to help me．
我宁可自己做也不劝他帮我。

③prefer to do sth.rather than do sth．
I prefer to do something rather than do nothing．
我愿意做点什么，不想什么也不做。

④prefer doing sth．to doing sth．
I prefer staying at home to watching such a dull play．
我宁愿待在家里，也不愿看如此乏味的戏剧。

too much
【原句回放】Indeed，he believes that a person with too much money has more rather than fewer troubles．事实上，他认为一个人有了太多的钱他的麻烦事只会更多而不是更少。

(P10)【点拨】too much的意思是“太多”，指超出正常，可以作表语、宾语、定语或状语(修饰动词)。

You have talked too much about it．
关于这件事情你讲得太多了。

(状语)
The noise was too much for me；I had to leave the room．
那噪音我受不了，我不得不离开那房间。

(表语)
They have eaten too much now；please stop them．
到现在他们吃得太多了，请让他们停下。

(宾语)
Americans eat too much meat，in my opinion．
依我看，美国人吃的肉太多了。

(定语)
【拓展】
much too为程度副词，修饰形容词或副词原级。

The question is much too difficult for such children．
这个问题对这些孩子来说太难了。

The students got to school much too late that day．
学生们那天到学校太晚了。

lead to
【原句回放】Not having enough food leads to poor health and，therefore，sickness．没有足够的食物导致身体很差，因此得病。

(P12)
【点拨】lead to
(1)相当于cause，意思是“引起；造成；导致”，其中to是介词，后跟名词、代词或动名词。

His laziness led to his failure in the final exam．
他的懒惰导致了他在期末考试中不及格。

The Car accident led to his being killed．那次车祸致使他死亡。

(2)作“通向”解。

This road leads to the foot of the mountain．这条路通向山脚下。

【拓展】
result in导致；结果是
result from起因于；由……造成；因……而产生
build up
【原句回放】These chemicals in the food supply build up in people’s bodies over time．随着时间的推移。

食物中的这些化学成分会在人体中堆积。

(P14)
【点拨】build up逐渐增加；增强(体质)；建立，开发；吹捧，赞扬
After4o’clock，the traffic begins to build up．
4点钟后，交通开始拥挤起来。

She built the business up from nothing．
她白手起家，生意日渐兴隆。

You need td build up your strength．你需要养精蓄锐。

You need more protein to build you up．
你需要更多的蛋白质来增强体质。

She’s built up a very successful business．
她已经建立了非常成功的生意。

The singer has been built up into a good success．
那个歌星已经被吹捧得很成功了。

in addition
【原句回放】In addition，fruit，vegetables and other food grown with chemical fertilizers usually grow too fast to be full of much nutrition．另外，施过化肥的水果、蔬菜和其他食物通常生长得过快而营养不足。

(P14)
【点拨】in addition“此外”是介词短语，作副词用，相当于词组as well，其后不能跟名词或其他任何成分，一般位于两个句子中间或位于句末。

位于两句中间时，常用逗号与句子隔开。

There are many shops around the railway station．In addition，there are some newly-built hotels there．
火车站附近有很多商店。

此外，那儿还有一些新建的旅馆。

Aunt Mary gave us sandwiches for our picnic and a bag of cookies in addition．
玛丽阿姨为我们去郊游准备了三明治，另外还准备了一袋甜饼。

【拓展】in addition to是介词短语，其后接名词或代词等作其宾语，意义大体相当于as well as和besides。

In addition to English，he has to study a second foreign language．
除了英语以外，他还必须学习第二外语．
They have one hour to read newspapers in addition to their ordinary work．
除了日常工作以外，他们有一小时读报的时间。

turn to
【原句回放】With these discoveries，some farmers and many customers are beginning to turn to organic farming．由于这些发现。

一些农民和消费者开始转向有机耕作。

(P14)【点拨】turn to变成；转向；翻到；求助于
His eager face turned to disappointment．
他热切盼望的表情变成了失望。

It’s time to turn to our work．该是我们工作的时候了。

Please turn to page120．请翻到120页。

Whenever you have difficulty，you can turn to me(for help)．
无论何时你有困难，都可以向我求助。

【拓展】
turn into(使)变成；翻译
turn against背叛
turn away把……打发走
turn down(音量等)调低；拒绝
turn in上交
turn off关上
turn on打开
turn out证明是；结果成为
turn over翻转
turn up开大音量；出席，到场
focus on
【原句回放】hey focus on keeping their soil rich and free of disease．他们关心的是保持土壤肥沃并且免受病害。

(P14)
【点拨】focus on集中；把……集中在……
I’m so tired I can’t focus on anything today．
今天我太累了，精神集中不起来。

【拓展】
be focused on(=concentrate on)集中精力、注意力
come into focus进入焦点
focus one’s attention on集中注意力于
bring...into focus把焦点聚焦于
keep...free from
【原句回放】This also helps the air，soil。

water and crops free from chemicals．同时还可以让空气、土壤、水以及农作物免受化学物质的污染。

(P14)
【点拨】keep...free from使……免受……
Constant exercise can keep you free from cold．
坚持体育锻炼会使你远离感冒。

【拓展】
keep in touch with...与……保持联系
keep sth./sb.out of sth.不让某物/某人入内，使某物/某人留在外面
keep out挡住，使进不去
keep back阻挡
keep an eye on sth．注意；看守；照看
keep...in mind牢记，放在心里
keep off使避开；使不要踩(或吃、谈等)；(雨、雪等)暂时不下
keep sb.from doing sth.阻止某人做某事
keep sb.doing sth.使某人不停地做某事
keep on doing sth.继续做某事
keep one’s word遵守诺言，履行某人已承担的保证或义务
keep silence保持安静，保持沉默
keep a secret保守秘密，守口如瓶
keep one’s head保持镇静
keep one’s mind on把注意力集中在……上
keep one’s temper不生气，按捺住性子，不发脾气
keep a firm(tight)hold(grip)on牢牢控制
keep up保持，持续
You keep on making the same mistake．
你总是犯同样的错误。

They kept on working in the field after dark．
天黑之后，他们还在地里劳动。

重点句型
so that可以引导目的状语从句
【原句回放】Now，many years later，Dr Yuan has another dream：to export his rice so that it can be grown around the globe．如今，多年之后，袁博士还有另外一个梦想，那就是看到他的稻谷可以出口并长遍全球。

(P10)
【点拨】so that可以引导目的状语从句，也可以引导结果状语从句，引导的目的状语从句既可位于句首又可位于句末。

so that引导的状语从句不表程度。

He got up early every day so that he could catch the early bus．
他每天都起得很早，以便能赶上早班车。

(目的状语从句)
He often came late to school so that he was often punished．
他经常上学迟到以至于他经常受到惩罚。

(结果状语从句)
【拓展】
目的状语小结
(1)不定式作目的状语
运用不定式表示“目的”是英语中最常用的方法，不定式的位置较随便，它既可以位于句首又可以位于句末，其否定形式在不定式前加not。

To catch the thief，the police searched the whole mountain．
为了抓住小偷，警察搜遍了整座山。

He went to Shanghai to see his brother．
他去上海看他的哥哥。

(2)用in order to或so as to结构引导目的状语
in order to或so as to比to do更能强调目的，其否定形式为in order not to或so as not to。

In order not to be late again，Jenny went to school without breakfast．为了不再迟到，詹妮没吃早饭就去上学了。

He gets up early every day so as to catch the early bus．
为了赶上早班车，他每天起得很早。

温馨提示
②so as to引导的不定短语不可置于句首。

②用in order to或so as．to结构时，不定式的逻辑主语必须与句子主语保持一致，若前后
主语不一致则必须用so that或in order that结构。

The school bus waited beside the village every morning so that the students could catch it on time．校车每天早晨都停在村子旁，以便学生们能准时坐上。