joint lever

例句：

1. 1. The joint leveris used to adjust the angle of thedoor.
   关节杠杆用于调整门的角度。
2. 2. Theengineer designed a joint lever that could liftheavy objects.
   工程师设计了一个可以举起重物的关节杠杆。
3. 3. The joint lever was crucialin the construction of the bridge.
   关节杠杆在桥梁的建设中至关重要。