twin pulley block

例句：

1. 1. The twinpulley block system is usedin the construction of bridges toallow for easy adjustment of the height.
   双滑轮块系统用于桥梁建设中，便于调整高度。
2. 2. The engineer used the twinpulley block to lift heavy objects withoutstraining his muscles.
   工程师使用双滑轮块来举起重物，而不致于拉伤肌肉。
3. 3. The twinpulley block was acritical component in the design ofthe new elevator system.
   双滑轮块是新电梯系统设计的关键部件。