2. 外语
  3. Once they decided to have children, MiShel and Carl Meissner tackled the next big issue: Should they try to have a girl? It was

Once they decided to have children, MiShel and Carl Meissner tackled the next big issue: Should they try to have a girl? It was

admin2017-11-17  67
问题     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
【C4】
选项
答案C
解析 此处应为动词过去式。本句的内容表明实验室的启动“标志”着该公司的第一次扩张，因此答案为marked。
转载请注明原文地址:https://kaotiyun.com/show/CHa7777K
0

大学英语四级

相关试题推荐
随机试题
最新回复(0)