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

What provides autos with electric power in an automated highway system ______.

A．A rail
B．An engine
C．A retractable arm
D．A computer controller

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