练习材料：
[Day 1653 2019-04-06]
L42-2: Modern cavemen
The deepest known cave in the world is the Gouffre Berger near Grenoble. It extends to a depth of 3,723 feet. This immense chasm has been formed by an underground stream which has tunneled a course through a flaw in the rocks. The entrance to the cave is on a plateau in the Dauphine Alps. As it is only six feet across, it is barely noticeable. The cave might never have been discovered had not the entrance been spotted by the distinguished French pot-holer, Berger. Since its discovery, it has become a sort of pot-holers' Everest. Though a number of descents have been made, much of it still remains to be explored. A team of pot-holers recently went down the Gouffre Berger. After entering the narrow gap on the plateau, they climbed down the steep sides of the cave until they came to a narrow corridor. They had to edge their way along this, sometimes wading across shallow streams, or swimming across deep pools. Suddenly they came to a waterfall which dropped into an underground lake at the bottom of the cave.
朗读时间：1’17/1’17
任务配置： L0+L4
知识笔记：
chasm 断层
Everest 珠穆朗玛峰
wade 涉水
练习感悟：
1 这篇为什么这么难？还发现一直读错了的known，忘记以前的发音跟着音标一节节的来。
2 发的不是最满意的，算是放水吧。
