单项选择题

It was ______ that asked Maury for help in oceanographic studies.

A．the American Navy
B．some early intercontinental travelers
C．those who earned a living from the sea
D．the company which proposed to lay an undersea cable

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热门试题

单项选择题

People tend to ignore the delayed effects of exposure to chemicals because

A．limited exposure to them does little harm to people's health
B．the present is more important for them than the future
C．the danger does not become apparent immediately
D．humans are capable of withstanding small amounts of poisoning

单项选择题

It can be concluded from Dr Dubos' remarks that ______.

A．people find invisible diseases difficult to deal with
B．attacks by hidden enemies tend to be fatal
C．diseases with obvious sighs are easy to cure
D．people tend to overlook hidden dangers caused by pesticide