tended to at a time in turn tune in data stream 打算,想 每次,一次 转而,依次,轮流 收听,作调谐 数据流
Abbreviations
IT(Information Technology) 信息技术 IP (Internet Protocol) 网际协议 PC (Personal Computer) 个人计算机 BBS (Bulletin Board System) 电子布告栏系统 AM (amplitude modulation) 调幅 DARPA (Defense Advanced Research Projects Agency) (美国国防部)高级研究计划署
Notes
(3) 强调状语 若被强调的部分是状语时,只能用that而不能用when或 where。请看下例： It was last year that he took over this company. 他是在去年接管了这家公司的。 It was in 1993 that he began to set up this private company. 正是在1993年他开始建立这家私人企业的。 It was not until yesterday that he did the experiment. 直到昨天他才做了那个实验。
Notes
(2) 强调宾语 It is light and heat that the sun gives us. 太阳供给我们的是光和热。 It was three printers that they bought last week. 他们上周买的是三台打印机。 注意，本句中的was不能换成were。
Exercises
请做课后练习
练习参考答案单独提供
Notes
[3] For the first time in the world history we had PC's that used the similar operating systems that allowed the computers' users to communicate by using the same platform. 本句中，that used the similar operating systems是一个定语 从句，修饰和限定PC's。that allowed the computers' users to communicate by using the same platform也是一个定语从 句，也修饰和限定PC's。
Unit 3
Information Technology
退出
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Phrases
Information Technology mobile phone word processing operating system be resistant to take off drop in 信息技术,缩写为IT 移动电话,手机 字处理 操作系统 对…有抗力 起飞;带领;拿去,去掉 下落,降低,顺便走访
Text
请老师朗读并讲解课文
Notes
[1] With recording technologies, transmission, and with early computers, it didn't take very long for scientific advances to merge together into the new field of information technology. 本句中，使用了It takes some time for sb. to do sth./It takes sb.some time to do sth.句型，意思是“某人花费时间做某 事”。在该句中，it是形式主语，真正的主语是动词不定 式短语to merge together into the new field of information technology。
Notes
[2] Before the 1990s, full time researchers having access to the high priced equipment drove most discoveries in information technology. 本句中，having access to the high priced equipment是一个 现在分词短语，作定语，修饰和限定full time researchers。 have access to的意思是“有权使用”。
Notes
注意，It is(was) ... that句型不能强调谓语。若要强调谓语， 需用助动词do。请看下例： Tom does look well. 汤姆看上去确实很健康。 Do come earlier next time. 下次一定要早点来。 They did work very hard last Sunday. 他们上星期天确实工作很努力。
Notes
[4] However, it was only with the invention of the microprocessor in the 1970s that computers became accessible to the public. 本句中，使用了it is/was… that/who强调句型。 在强调句型中，着重强调句子的某一部分，如主语、宾 语或状语。 (1) 强调主语 当强调的主语是人时，强调句型中的that可以换成who。 当主语是人称代词时，一定要注意人称代词的格：在正 式的英语中，只能用主格；而在非正式的英语中，有时 也可使用宾格。