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

It can be concluded from the passage that the author's attitude toward sex selection is ______.

A．negative
B．positive
C．neutral
D．favorable