问题
选择题
They use computers to keep the traffic smoothly.
A．being run
B．run
C．to run
D．running
答案
答案：D
考查非谓语动词Ving，这儿构成(keep sth. doing。)。
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They use computers to keep the traffic smoothly.
A．being run
B．run
C．to run
D．running
答案：D
考查非谓语动词Ving，这儿构成(keep sth. doing。)。