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According to Hahn, all the following increase the transmission of AIDS virus EXCEPT

A．hunting and killing more chimpanzees.
B．more champ hunters moving to cities.
C．people's changed sexual behaviours.
D．travelling to more African countries.

单项选择题Many AIDS experts are not completely satisfied with results of the study because

A．only a limited number of chimpanzees are used for sampling the virus.
B．it is now extremely difficult to find chimpanzees that carry the virus.
C．the samples collected are from two different subspecies of chimpanzees.
D．it does not provide reliable evidence of the link between SIV and HIV-1.

单项选择题One of the results of grief mentioned in the passage is

A．loss of friendships.
B．diminished socializing.
C．vulnerability to disease.
D．loss of appetite.

单项选择题The researches reviewed in the passage suggest that

A．remarried men live healthier lives.
B．unmarried men have the longest life spans.
C．widowers have the shortest life spans.
D．widows are unaffected by their mates' death.