单项选择题

Girl sperm was preferred to boy sperm in the research most probably because ________.

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

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热门试题

单项选择题

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

单项选择题

Of tackling obesity in the poor world, we can learn from the passage that ________.

A．the matter is so complex as to go beyond our capacity
B．no matter what we do, the prospect will always .be bleak
C．it is starvation, the real threat, that needs to be solved
D．we should take immediate actions before it becomes incurable