框架需要足够坚固以支撑发动机的组装。

The frame needs to be strong enough to support the engine ___assembly.

沙发组装中三个座位之一下面的弹簧似乎也坏了。

The spring beneath one of the 3 seats integrated with the sofa ___assembly also seems to be broken.

飞机的最终组装需要精确度和技能。

The final ___assembly of the aircraft requires precision and skill.