plunger helix

例句：

1. 1.The engineer designed a plunger helix to help the workers lift heavy objects.
   工程师设计了一个投石机螺旋，帮助工人举起重物。
2. 2. The plunger helix was used in ancient times to break rocks and open caves.
   投石机螺旋在古代被用来打破岩石和开辟洞穴。
3. 3. The engineer carefully adjusted the plunger helix to ensure it worked smoothly.
   工程师仔细调整投石机螺旋，确保其工作顺畅。