3. B。判断题。从文章第2段第2句话…the answer depends on technology and our ability to use it widely 可以肯定答案选B。

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Space travel is definitely bad for astronauts’ bones, reducing their bone density(密度) after only a month of weightlessness, according to French research published on Friday.

Laurence Vico and his fellow workers at St Etienne University called for more research into the effects of microgravity, after their study of 15 astronauts from the Russian MIR station showed bone loss continued throughout space flights.

“Bone loss was especially striking in four astronauts, ” the scientists reported in the Lancet Medical Journal.

They measured the bone mineral density (BMD) of bones in the forearm(前臂) and lower leg of the astronauts who had spent one to six months in space.

The BMD loss was significant in the tibia(胫骨) of the lower leg, a weight-bearing bone, but barely changed in the radius(桡骨) of the forearm. “Our results indicate the need to investigate not only different bones, but also different areas of the same bone since not all sites of the skeleton (骨架) are similarly affected by space conditions, ” they added.

Without gravity the body isn’t bearing any weight so there is no need for calcium (钙) which makes bones strong, and it becomes empty into the bloodstream.

The research team suggested in future scientists should try to determine if the loss of bone density was only on weight-bearing bones on longer flights, also the possible recovery after returning to Earth.

4. A。判断题。根据最后一句话The air is more moist(潮湿) in the tropics(热带) than in the cold polar regions 可知答案。

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Technology is the application(应用) of knowledge to production. Thanks to modern technology, we have been able to increase greatly the efficiency of our work force. New machines and new methods have helped cut down time and expense while increasing overall output. This has meant more production and a higher standard of living. For most of us in America, modern technology is thought of as the reason why we can have cars and television sets. However, technology has also increased the amount of food available to us, by means of modern farming machinery and animal breeding techniques, and has extended our life span via(通过) medical technology.

Will mankind continue to live longer and have a higher quality of life? In large measure the answer depends on technology and our ability to use it widely. If we keep making progress as we have over the past fifty years, the answer is definitely yes. The advancement of technology depends upon research and development, and the latest statistics(统计) show that the United States is continuing to pump billions of dollars annually(每年) into such efforts. So while we are running out of some scarce resources(少的资源) we may well find technological substitutes(代用品)for many of them through our research programs.

Therefore, in the final analysis the three major factors of production(land, labor and capital) are all influenced by technology. When we need new skills, on techniques in medicine, people will start developing new technology to meet those needs. As equipment proves to be slow or inefficient, new machines will be invented. Technology responds to our needs in helping us maintain our standard of living.

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