单项选择题

Britain was able to establish itself as a world leader ……

Britain was able to establish itself as a world leader in shipbuilding in the middle of

A．the 16th century.
B．the 17th century.
C．the 18th century.
D．the 19th century.

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热门试题

单项选择题The Victorian Age, eminently represented by Dickens and Thackeray, was mostly regarded as an age of ______ in English literature.

A．epic prose
B．drama
C．poetry
D．novels

单项选择题Since chimpanzees are genetically very similar to humans,

A．chimpanzees are likely to suffer AIDS just like humans if they are infected.
B．it does not matter if human beings are infected with SIV rather than HIV-1.
C．we can use human vaccines to prevent chimpanzees from getting AIDS virus.
D．AIDS vaccines based on chimp's immune mechanism are possible to be made.

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.

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.