sodium-potassium geothermometer

例句：

1. 1. The sodium-potassium geothermometer was used to measure the temperature of the earth's core.
   钠钾地温计被用来测量地球核心的温度。
2. 2. The geothermometer was used to determine the depth of the underground caverns.
   地温计被用来确定地下洞穴的深度。
3. 3. The geothermometer was used to monitor the temperature changes in the Earth's crust.
   地温计被用来监测地球地壳的温度变化。