问题
选择题
They are broadening the bridge to ________ the flow of traffic.
A．put off
B．turn on
C．speed up
D．work out
答案
答案：C
题目分析：考查动词短语：A. put off推迟，B. turn on打开，C. speed up加速，D. work out制定出，句意：他们正在加宽这座桥，来加速交通的流量。选C。