【题目】They use computers to keep the traffic________smoothly.
A.being run
B.run
C.to run
D.running

【答案】D
【解析】句意：他们用电脑使交通运转顺畅。keep＋宾语＋宾补，此处traffic与run之间为主谓关系，故用现在分词作宾补。