方向盘组件作为独立部件生产后，再安装到整车中。

The steering wheel is manufactured as a ___sub-assembly before being installed in the complete vehicle.

工人们先将发动机作为子组件装配好，然后再安装到汽车底盘上。

The workers first assembled the engine as a ___sub-assembly before installing it onto the car chassis.