同学你好，该知识点来自沪江网校《新概念英语第三册【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好：
这两个词的来源——
The term stalactite comes from the Greek word stalaktos, which means “dripping”, because these other-worldly formations are produced by “drips” from the ceilings of limestone caves. Water reacts with chemical elements in the ground and rock, and seeps slowly through the roof of the cave, depositing calcium carbonate, which hardens and builds up over time to form a stalactite.

Stalagmites are corresponding formations on the floors of caves, rising up over time as drops of water, rich in calcium carbonate, fall from the roof of the cave. The term stalagmite comes from the Greek word, stalagma, to “drop”.
怎么记住它们 ——

Stalactite has a “c” for “ceiling”
Stalagmite has a “g” for “ground”
Stalactites hang “tite” to the ceiling above
Stalagmites “mite” grow all the way to the ceiling

供参考～

祝学习愉快！