一列警车为总统的豪华轿车开道，其他车辆则尾随其后。

A string of police cars led the president’s limousine, and others ___trailed behind.

那艘小帆船跟随着大帆船穿过了广阔的海湾。

The small sailboat ___trailed the larger one across the vast bay.

我们的科技飞速进步，但有时我们的道德框架似乎远远落后。

Our technology advances rapidly, but sometimes our ethical frameworks seem to ___trail far behind.