2. 外语
  3. Henry III didn’t know much about biology. He went through six wives back in the 1500s, looking for one who could bear him a son.

Henry III didn’t know much about biology. He went through six wives back in the 1500s, looking for one who could bear him a son.

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问题     Henry III didn’t know much about biology. He went through six wives back in the 1500s, looking for one who could bear him a son. Scientists now know that it’s the father’s sperm, not the mother’s egg, which determines whether a baby is a boy or a girl. And last week researchers at the Genetics and IVF Institute, a private fertility(生育能力)center in Virginia, announced a new technique that will allow parents to choose the sex of their baby-to-be,  before it has even been conceived. The scientist used a tiny laser detector to measure the DNA in millions of sperm cells as they pass single file through a narrow tube, like cattle being herded through a corral(牲口栏). In a study published last week, "girl sperm," which has more DNA—the genetic material— in each cell, was collected, while "boy sperm" was discarded. And when purified girl sperm was used to impregnate(使受孕)a group of mothers, 15 of 17 resulting babies turned out to be girls.
    The researchers say that "sex selection" can also double a mother’s chance of having a son and can be used to avoid genetic diseases that affect only one gender, such as hemophilia(血友病). But some experts, like New York University fertility specialist Dr. Jamie Grifo, worry that sex selection could lead to a kind of in uteri(子宫)discrimination, especially in cultures where sons are considered superior to daughters. "It’s valuing one gender’ over another," Grifo says. "I don’t think that’s something we should be doing." So far, patients at the institute have been asking for both boys and girls, in order to "balance" their families. And some ethics experts say that’s fine, as long as parents are just looking for a little gender variety. "If you have three boys, and you want a girl," says University of Texas reproductive-law professor John Robertson, "that’s not gender bias at all."
Girl sperm was preferred to boy sperm in the research most probably because ______.
选项 A、girl sperm contains more genetic material
B、more mothers want to have girl babies
C、girl sperm is healthier and more active
D、girl sperm is more easily purified
答案A
解析 该句中的由which引导的定语从句表明选项A的叙述正确。
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