indicating needle

例句：

1. 1. The doctor used apointing needle to help her find the painin her back.
   医生用一个指示针帮助她找到背部的疼痛。
2. 2. The scientistused an indicating needle to measure the concentrationof chemicals in the sample.
   科学家用一个指示针来测量样本中化学物质的浓度。
3. 3. The engineer used an indicating needle tomark the location of the crack on thewall.
   工程师用一个指示针来标记墙上裂缝的位置。