Many people wonder why some men want to live on the moon It is【C1】______not the kind of place where most men would choose to live. But man has always moved to new areas. Some scientists hope that continued work will be done on the moon. Many experiments will be done there more【C2】______. Some large【C3】______are very easy to do in a place without air. Matter can be heated to very high temperatures without【C4】______change when it is in such a place. Air, dust, and clouds cannot【C5】______man’s view of space from the moon. The very high or very low temperatures and low gravity on the moon will be used for many experiments. One very important use of the moon will be to【C6】______spaceship. Man might be able to learn much about his own body by living on the moon. He would be living in a habitat that he made for himself. Man would be in control of the【C7】______of life in which he lives.【C8】______could be removed from the air in this community. Gravity is the one thing that would not be under man’s control. Some scientists believe the low gravity of the moon would be【C9】______for man. The heart would not have to work so hard. The body would need less energy to move than it does on the earth However, the human body might change during long stays on the moon Much exercise would probably be needed to keep the body in good【C10】______. A. community B. condition C. launch D. insight E. chemical F. mysterious G. experiments H. probably I. healthful J. easily K. extend L. render M. promptly N. block O. bacteria

Once they decided to have children, MiShel and Carl Meissner tackled the next big issue: Should they try to have a girl? It was no small matter. MiShel’s brother had become blind from a hereditary condition in his early 20s, and the Meissners had learned that the condition is a【C1】______passed from mothers to sons. If they had a boy, he would have a 50 per cent chance of having the condition. A girl would be【C2】______. The British couple’s inquiries about gender selection led them in 1999 to Virginia, US where a new sperm (精子)-separation technique, called MicroSort, was under【C3】______. When MiShel became pregnant, she gave birth to a daughter. They will try to have a second daughter using the technique later this year. The technique separates sperm into two groups—those that carry the X-chromosome (producing a female baby) and those that carry the Y-chromosome (producing a male baby). The technology was developed in 1990s, but last month’s opening of a laboratory in California【C4】______the company’s first expansion. “We believe the number of people who want this technology is greater than those who have【C5】______to it,“ said Keith L. Blauer, the company’s clinical director. This is not only a【C6】______effective way to select a child’s gender. It also brings a host of ethical (伦理的) and practical considerations—especially for the majority of families who use the technique for【C7】______reasons. The clinic offers sex selection for two purposes: to help couples avoid passing on a gender-linked【C8】______disease and to allow those who already have a child to ’balance“ their family by having a baby of the opposite sex The technology is still【C9】______. However, Blauer says the company has an impressive success rate: 91 per cent of the women who become pregnant after sorting for a girl are successful, while 76 per cent who sort for a boy and get pregnant are successful. The technique separates sperm based on the fact that the X-chromosome is larger than the Y-chromosome. A machine is used to【C10】______the size differences and sort the sperm accordingly. The result is then checked using another type of DNA analysis to ensure that it contains mostly X-or Y-bearing sperm. The desired sample is then used for artificial insemination (授精) or test tube fertilization. A. genetic B. overlapped C. marked D. unaffected E. perpetually F. investigation G. access H. feat I. disorder J. gropes K. experimental L. seemingly M. elicit N. nonmedical O. distinguish

The greenhouse effect causes trouble by raising the temperature of the planet. The【C1】______rise is not very much, but the Earth’s ecosystem is very weak, and small changes can have large effects. It has been believed that this【C2】______of one degree will happen by the year 2025. This could probably【C3】______the North American corn belt, which produces much of the world’s grain,【C4】______to much higher food prices, and even less food for the Third World than they already have. However, it would also mean that some countries which are further north would be able to【C5】______crops they had never been able to before, although there is less land as you move north from the corn belt. The other serious worry is that rising sea levels from the melting of the polar ice could【C6】______flood many countries. A rise in sea levels of one meter, which many experts are【C7】______by the year 2100 (and some as soon as 2030), would flood 15 percent of Egypt, and 12 percent of Bangladesh. The Maldives in the Indian Ocean would almost【C8】______disappear. Most of the countries which would suffer most from a rise in sea levels are the poor【C9】______states, so the islands in the Caribbean, South Pacific, Mediterranean and Indian Ocean have formed the Alliance of Small Island States, AOSIS, so they have a【C10】______voice in international politics and can make the richer developed world listen to their problems. A. severely B. damage C. island D. critical E. grow F. mainland G. louder H. predicting I. rise J. completely K. geometry L. actual M. extending N. leading O. develop