结构推理 Congestion makes things worse: Cars caught in traffic jams pollute three times as much as those on the open road.
【正确答案】stuck in
【答案解析】[译文] 交通拥挤让事情变得更糟：陷入交通堵塞的车辆所排放的污染物是在畅通的公路上通行车辆的3倍。