警方正在追捕那些持刀胁迫司机并劫走汽车的劫车犯。

The police are chasing the ___carjackers who threatened the driver with a knife and stole the car.

最近有几名劫车犯在高速公路上专门针对卡车司机作案。

Several ___carjackers have been targeting truck drivers on the highway recently.