单项选择题

The biggest worry that the researchers now have is ______.

A．more and more wild chimpanzees are being slaughtered.
B．AIDS virus is difficult to be killed and controlled.
C．it is not easy to repair people' s deficient immune systems.
D．many dangerous viruses are being transmitted to humans.

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单项选择题

The significance of the finding is that ______.

A．people now know the number of chimpanzees is much smaller than expected
B．it may make it possible for scientists to discover new ways of treating AIDS.
C．it proves some deadly human diseases can also be transmitted to wild animals
D．it will soon help the scientists develop a vaccine that prevents the AIDS virus

单项选择题

What does the word hip mean in this passage

A．It is derived from "hippie".
B．It means following the social fashion in the 1960s and 1970s.
C．It comes from a more recent useage.
D．It means “out - of - date slang”.