AC(alternating current) 交流(电) A／D(analog to digital) 模拟／数字转换 ADC(analog to digital convertor) 模拟／数字转换器 ADM(adaptive delta modulation) 自适应增量调制 ADPCM(adaptive differential pulse code modulation) 自适应差分脉冲编码调制

The purpose of a receiver is to select a desired group of frequencies from one transmitter, get rid of all unwanted signals and noise, and then demodulate the signal to obtain the modulating infomation. The better the receiver does its job, the closer the demodulated sigmal will resemble the original signal from the transmitter. Regardless of the type of demodula

1. grasp the main idea( tolerance for solitude and energy made it possible for the writer s family to enjoy their pleasant but sometimes harsh country life.) 2. appreciate the various techniques employed by the writer comparison and contrast, topic sentences followed by detail sentences

And so even though we face the difficulties of today and tomorrow, I still hay a dream. It is a dream deeply rooted in American dream. I have dream that one day this nation will rise up and live out the true meaning of

violent crimes robbery, aggravated assault hijack forcible rape, murder, bombing kidnapping, shooting a Property crimes arson, burglary, larceny-theft, fraud, motor/ vehicle theft Neighborhood Watch in Britain, there is an arrangement by which people who live in a particular

At least 90 percent of UFO sightings can be identified as conventional objects, although time-consuming investigations are often necessary for such identification. The objects most often mistaken for UFOs are bright planets and stars aircraft, birds, balloons kites aerial flares, peculiar clouds, meteors and satellites. The remaining sightings most likely can be attributed to other mistaken sightings or to inaccurate reporting hoaxes or delusions although to disprove all claims made about UFOs is impossible

Students will be able to 1. understand the main idea and the structure of the text. 2 earn to memorize words in association 3. grasp the key language points and grammatical structures in the text 4. conduct a series of reading, listening speaking and writing activities related to the theme of the unit

Students will be able to: 1. understand the main idea and structure of the text; 2. appreciate how the repeated use of clues helps weave a piece of narration together; 3. grasp the key language points and grammatical structure in the text

Objectives Students will be able to: 1. understand the main idea(cloning is a two- edged sword) and structure of the text; 2. appreciate the writing strategies employed by the author, 3. master the key language points and grammatical structures in the text;

Objectives Students will be able to: 1. understand the main idea (Bill Porter the salesman will never give in) and structure of the text (4 parts, 2 flashbacks); 2. appreciate the characteristics of journalistic writing; 3. grasp the key language points and grammatical structures in the text;