The protesters stopped vehicles and asked drivers for their operating permits.

抗议者拦下车辆并要求司机出示驾驶证。

However, three out of four vehicles failed a test in which a lead vehicle changed lanes, causing a stopped vehicle to suddenly appear.

但是，在前面有车改变车道导致一辆停下的车突然出现时，四辆测试车辆中有三辆都未能躲避。