step_by_step3000第三册unit6答案及原文word文本

Unit 6 Science and Technology

Part I Warming up

A1.

Tapescript.

1. Thai silk is known for its beauty and elegance. But a research team has found a new use for it. A bulletproof vest made of silk was put to the test at a shooting range in Thailand. After several rounds of gunfire, the vest was examined. The bullets were stuck in the first layer of fifteen pieces of silk. A member of the research team says while silk threads may be soft, they can be used to produce a stronger yarn than copper threads, the material used in regular bulletproof vests.

2. American and Japanese researchers say they are a step closer to predicting severe weather in and around the Indian Ocean. Researchers have analyzed weather data from the region over the past 40 years and they've discovered a strong connection between extreme weather and conditions in the ocean. A BBC science correspondent says the findings could make it easier to predict droughts or, indeed, periods of heavy rainfall.

3. The world chess champion Garry Kasparov began a match against the rest of the world on the Internet. Kasparov made his first move with a meter-high pawn before an audience of chess fans at a park in New York. The move was immediately posted on a special website set up by the Microsoft corporation. Visitors to the site have 24 hours to vote on their counter move helped by a team of young chess experts who will suggest strategies.

4. Few scientific advances of this or any millennium can rival in significance the discovery of the structure of DNA, the basic molecule of life. Knowledge of the structure of DNA helps explains many things, including genetic mutation and , through it, evolution. Understanding its code has helped to unlock the mechanics of inherited disease, as well as beneficial biological traits such as intelligence and body strength. The discovery of the DNA molecule also paved the way for many of today’s cutting-edge sciences, including genetic engineering, a controversial branch of knowledge that raises new ethical and moral questions that are certain to be with us far into the next millennium.

5. Some say it's hard to find good help these days, but a Japanese electronics firm thinks it's found the answer. It's a robot that talks and understands orders. The robot from NEC can record and send video mail through the Internet and switch on TVs and VCRs. And if it's becoming a bit warm for you, one simple command and the robot will switch on the air conditioner.

B.

Tapescript:

1 .... Yes, you see, it's the force of attraction between any two objects. The strength of the force depends on the mass of the objects and the distance between them. Er... the most obvious effect is the way objects on the surface of the earth are attracted towards the center of the earth...

2 .... as it comes down it goes relatively slowly 100 to 1,000 miles per hour and you can't see it, but the return stroke goes up from the earth to the cloud and it goes at over 87,000 miles per hour and that's the one you can see, you see, the one that goes back up. It's really just a very large, powerful spark. The distance in miles you are away from it is the time in seconds between it and the sound you hear...

3 .... Well, they were first discovered in 1895 and they can penetrate matter that is opaque to light. Some matter is more transparent to them than others, which means you can see inside somebody. They are actually quite dangerous and people who work with them wear special protective clothing...

4 .... ordinary light consists of electromagnetic waves of different frequencies and phase(s). This is a