2. 考研
  3. In 1 999 when MiShel and Carl Meissner decided to have children，they tackled the next big is sue：Should they try to have a girl?

In 1 999 when MiShel and Carl Meissner decided to have children，they tackled the next big is sue：Should they try to have a girl?

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问题 In 1 999 when MiShel and Carl Meissner decided to have children，they tackled the next big is sue：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 20 s，and the Meissners had learned that the condition is a disorder passed from mothers to sons．If they had a boy．he would have a 50 percent chance of having the condition．A girl would be unaffected.The Briti．sh couple’S inquiries about sex selection led them to Virginia，U．S．，where a new sperm separation technique，called MicroSort，was experimental at the time  When MiShel became pregnant she gave birth to a daughter．Now they will try to have a second daughter using the same technique  The technique separates sperm into two groups--those that carry the X’chromosome producing a female babv and those that carry the Y．chromosome producing a male baby．
The techn010gy was developed in 1 990s，but the opening of a laboratory in January 2003 in California marked the company’s first expansion．“We believe the number of people who want this technology is greater than those who have access to it，”said Keith L．  Blauer，the company’s clinical director．
  This is not only a seemingly effective way to select a child’s gender．It also brings a host of ethical and pI．actical considerations--especially for the majority of families who use the technique for nonmedical reasons．
The clinic 0fiers sex selection for two purposes：to help couples avoid passing on a sex—linked  genetic disease and t0 allow those who already have a child to“balance’’their family by having a baby of the opposite sex．
    Blauer said the company has had an impressive success rate：9 1 percent of the women who beccome pregnant after sorting for a girl are successful，  while 76 percent who sort for a boy and get pregnant are successful．
The technique separates speitll based on the fact that the X chromosome is larger than the Y．
Chromosome A machine is used to distinguish the size differences and sort the sperm accordingly．
When MiShel gave birth to her first girl，the new sperm—separation technique_________
选项 A、had already been well—developed
B、had not been declared successful
C、was available to those who wanted it
D、had been widely accepted in the medical world
答案B
解析 第一段第六句提到：因为这对英国夫妇要求选择孩子的性别，因此他们就来到了美国弗吉尼亚州，这里有一种新的分离精子的技术称作MicroSort(微筛选)，当时正在试验阶段(指1999年)。
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