英語四級閱讀練習附答案-34 決定嬰兒性別

　　Henry III didn't know much about biology. He went through six wives back in the 1500s, looking for one whocould 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(牲口欄). 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 usedto 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 ofin uteri(子宮)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."

　　練習題：

　　Choose correct answers to the question:

　　1.The DNA in the sperm cells can be measured ______.

　　A.in the same way how the cattle are herded

　　B.when they pass through a tube one behind the other

　　C.after they pass through a laser tube

　　D.when they are scanned by a laser detector all at a time

　　2.The gender of the baby is decided by ______.

　　A.the father's DNA

　　B.the mother's DNA

　　C.the father's sperm

　　D.the mother's egg

　　3.According to this passage, the practice of "sex selection" ______.

　　A.can help to prevent all genetic problems

　　B.is totally unacceptable to ethics experts

　　C.was already realized five hundred years ago

　　D.will benefit families with certain inheritable diseases

　　4.Girl sperm was preferred to boy sperm in the research most probably because____

　　A.girl sperm contains more genetic material

　　B.more mother want to have girl babies

　　C.girl sperm is healthier and more active

　　D.girl sperm is more easily purified

　　5.It can be concluded from the passage that author’s toward”sex selection”is____

　　A.negative

　　B.positive

　　C.neutral

　　D.favorable

　　1.[B] 推理判斷題。解答本題的關(guān)鍵在于推斷single file的意思。該句把精子通過試管的情形與牛群被趕入牲口圈的情形作對比，結(jié)合single一詞本身的意思，可以推斷single file是“一個接一個”的意思，只有選項B能表達這個意思，由此也可否定選項D。選項A最具干擾性，原句是把精子通過試管的情形比作牛群被趕人牲口圈的情形，而選項A說的是測定精子內(nèi)DNA的方法與放牧的方法相同，顯然選項A只是引用了原文的某些詞語，但表達的意思與原文卻截然不同。

　　2.[C] 事實細節(jié)題。第1段第3句which引導的非限制性定語從句修飾的是the father's sperm，而不是插入語the mother’s egg,因此選項C正確。

　　3.[D] 推理判斷題。第2段第1句中的genetic暗示有些疾病是遺傳的，即如選項D所述。第2段第1句同時表明選項A的說法是不全面的。選項B與第2段最后兩句正好相反。第1段前兩句說明選項C是錯誤的。

　　4.[A] 事實細節(jié)題。第1段倒數(shù)第2句中的由which引導的定語從句表明選項A的敘述正確。

　　5.[C] 觀點態(tài)度題。文章第2段中作者給出了一些反對者和贊成者的觀點，但是沒有加以評論，可以看出作者的態(tài)度是中立的，故選項C正確。