lever of maximum stability

例句：

1. 1. The engineer used a lever to lift the heavy box.
   工程师用一个杠杆抬起了沉重的箱子。
2. 2. The doctor used a lever to lift the patient's bed.
   医生用一个杠杆抬起了病人的床。
3. 3. The carpenter used a lever to move the heavy table.
   木匠用一个杠杆移动了沉重的桌子。