工人们正在费力地将这些沉重的箱子拖上卡车。

The workers are ___hauling these heavy boxes onto the truck.

工人们正在费力地把沉重的箱子拖上卡车。

The workers were ___hauling the heavy boxes onto the truck.

他们用卡车长途运输农产品到城市。

They use trucks for ___hauling agricultural products to the city over long distances.