单项选择题

How has the use of helicopters developed

A．They have been widely used for various purposes.
B．They are taking the place of high-flying jets.
C．They are used for rescue work.
D．They are now used exclusively for commercial projects.

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单项选择题

Where is the engineer who realized the ancient-dream from

A．China
B．Italy
C．Canada
D．Russia

单项选择题

People expect that ______.

A．the airliners of today would eventually be replaced by helicopters
B．helicopters would someday be able to transport large number of people from place to place as airliners are now doing
C．the imaginations fired by the Russian engineer's invention would become a reality in the future
D．their fantastic expectations about helicopters could be fulfilled by airliners of today