单项选择题

What is the author's main concern

A．How to render automobiles pollution-free.
B．How to make smaller and safer automobiles.
C．How to solve the problem of traffic jams.
D．How to develop an automated subway system.

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热门试题

单项选择题

In an automated highway system, all the driver needs to do is ______.

A．keep in the right lane
B．wait to arrive at his destination
C．keep in constant touch with the computer center
D．inform the system of his destination by phone

单项选择题

One significant improvement in the future car will probably be ______.

A．its power source
B．its driving system
C．its monitoring system
D．its seating capacity