2. 外语
  3. When Louise Brown was born on 25 July 1978, she kicked off an era. The first "test tube baby" is a mother herself now, and she’s

When Louise Brown was born on 25 July 1978, she kicked off an era. The first "test tube baby" is a mother herself now, and she’s

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问题     When Louise Brown was born on 25 July 1978, she kicked off an era. The first "test tube baby" is a mother herself now, and she’s been joined by millions of others born with the【S1】______of in vitro fertilization(体外受精), or IVF. Now specialists wonder whether people who were conceived by IVF are likely to be【S2】______.
    "By and large, the kids are just fine. It’s not like the kids having【S3】______arms or heads," says Carmen Sapienza, a scientist at Temple University. But none is older than their early 30s, and the vast【S4】______are under the age of 20, so they haven’t had time for long-term health problems to show up.
    One source of worry is that so many IVF babies have low birth weight. Children-conceived through IVF are more likely to【S5】______less than 2.5 kilograms than are babies conceived【S6】______. That could spell trouble ahead, because low-birth-weight babies often have long-term health problems. They’re more likely to be obese, to have diabetes(糖尿病)or other problems.
    With that in mind, Sapienza and colleagues have looked at genes that are likely to play a role in such health problems. They found that certain DNA-patterns, which affect how genes are【S7】______, are different between IVF and non-IVF children. There’s no way to tell if that’s because of the【S8】______used to produce the IVF babies or whether the difference has something to do with the underlying infertility problem the parents had. It’s also【S9】______whether these gene-expression differences will translate into health differences. But it does suggest that children conceived by IVF are【S10】______on some level.

A)weigh         B)technology     C)help         D)unsure         E)unclear
F)naturally     G)expressed      H)procedure    I)unique         J)healthy
K)explained     L)extra          M)majority     N)minority       O)completely
【S9】
选项
答案E
解析 此处应为形容词，作表语。空后的whether表明不确定性，词库中unsure和unclear都含有“不确定”之义，但是unsure的主语一般为人，unclear的主语一般为物，根据句子的主语It可知应选unclear。
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大学英语四级

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