本课简介
技术是否也是一把双刃剑，在给人们带来帮助的同时也带来了弊端?本课通过卫星通讯的利弊昭示人们“明智”地运用技术才能使我们走向成功。
卫星、计算机和电视的三结合改变了人们的生活。卫星被用来传送电视节目、电话和印刷材料;卫星被用于远程教育，使边远地区的人们通过“空中教室”接受教育;卫星被用来帮助生活在交通不便的偏僻地区的人们;卫星使世界各地的人们便捷地获取信息。然而侵犯隐私、使人与人之间疏于接触交流等弊端也应引起关注。
本课主要语言点
1.At the beginning of the twentieth century，there were four powerful means of transmitting and receiving information over long distances：…
本句中的beginning是一个名词，意思是“开始，开端”。如：
means在本句中的意思是“方法;工具”
by all means尽一切办法
live within/beyond one's means量入(不量入)为出
a means to an end达到目的的方法
by some means or other用某种方法
2.By the middle of the century，both radio and television had become established means of transmitting sounds and pictures.
句中所用的过去完成时，表示过去某时前已经发生的动作或情况。该动作已经完成，或者可能延续下去。用by引起的时间状语常与过去完成时连用。例如：
1)By the end of last June，they had visited 15 countries.(到去年六月底为止他们已经访问了15个国家。)
2)By the end of last year Henry had collected 1500 butterfly specimens.(到去年年底，亨利已经采集了一千五百多个蝴蝶标本。)
established在句中做形容词，意思是“常规的”。这个词还可解释为“(被)设立的;确认的;既定的;公认的”。例如：
1)a newly established organization(新设的组织)
2)the established principles of international law(公认的国际法准则)
3)an established fact(既成事实)
4)an established custom(常规)
3.In order to transmit an event such as the Olympics Via satellite，television signals are first changed into radio waves，which are then sent from a station on earth to an orbiting satellite.
such as的后面既可以跟名词也可以跟从句，意为“诸如…之类的”;“例如”或“像…这样的人或事物”
which引导的是一个非限定性的定语从句。非限定性定语从句在修饰人时用who，whom或whose，在修饰物时用which.非限定性定语从句常用逗号与主句分开
非限定性定语从句也可用关系副词where或when来引导。非限定性定语从句的先行词可以是一个词，也可以是前面主句中的一个短语、从句或前面整个句子，通常用关系代词which引导。
4.In theory，every person will have access to an unlimited amount of information.
in theory意为“从理论上来说;在理论上”，与其意思相反的词组是in practice(在实践中;实际上)。
have access to是一个很常用的词组，意为“可接近，可进入”，to是介词，动词have也可用其他词替换。如get，gain，give，win等。
information是一个不可数名词，后面不可以加s，许多信息可以用a lot of information，a large amount of information，much information等表达。一条信息可以表达为a piece of information.
amount通常用在不可数名词前面，如the amount of money;a considerable amount of prejudice(相当大的偏见)。在复数名词前面可用number，如the number of mistakes;the number of students
5.The satellite also demonstrated how it could provide help to people living in isolated areas where transportation is difficult.
how引导的是一个宾语从句。我们很熟悉的是that引导的宾语从句，而且that常常可以省略。如：We must remember(that)things are easier said than done.(我们必须记住事情都是说起来容易，做起来难。)
用连接代词或副词引导的宾语从句我们也应弄清楚。
provide是一个常用单词，通常可以有如下用法：provide sth.to/for sb.;provide sb.with sth.;provide sb.sth.;provide that…，在前一个单元中，我们已对provide一词有过讲解
6.He was then able to follow the doctor's instructions on how to care for the patient.
句子中的on意思为“关于;有关”，可用about替换
care of在句子中的意思是“照顾”，可用attend;look after替换。
care for还可以解释为“担心”，“介意”，“愿意”，可用about替换for.
1)He doesn't care about/for his clothes.(他不讲究衣着。)
2)The old lady cared much for her daughter's safety.(老太太非常为女儿的安全担心。
7.The most common use of telecommunication satellites，however，has been for transmitting telephone calls.however
在本句中做副词用，意思相当于but.但是however和but在用法上是有差异的。however不放在句首或句末时，前后通常都加逗号，而but则不用。请看例句：
1)It is not，however，the only answer to the question.(然而，这不是问题的唯一答案。)
2)I am sorry，but I won't be able to come this time.(很报歉，我这次不能来了。)
8.Telecommunication can make information from around the world available to use quickly and easily，but some people worry that this may be a risk to our privacy.
available是一个形容词，意思是“可得到的;可用的;有效的”。
1)I am sorry those shoes are not available in your size.(很报歉，那些鞋没你的尺码。)
2)If I am not available when you call，leave a message.(你打电话来时如果我不在，请留个言。)
9.We can prevent this from happening by carefully controlling the new technology.
prevent…from…意思为“阻止…发生”，也可用stop…from…或keep…from.From在前两个短语中可被省去。
Nothing can prevent him(from)going there.(什么也阻止不了他去那儿。)
本课主要词组及语法要点
词组：
1.at the beginning of 2.means of
3.over long distance 4.by the middle of
5.such as 6.change into
7.from…to…8.be capable of
9.not only…but…10.in theory
11.have access to 12.amount of
13.provide…to…14.follow sb's instructions
15.care for 16.as well as
17.at the same time 18.make…available
19.pay for 20.isolate…from…
考试提醒 
