练习材料：

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.

系统故障。

任务配置：

L0＋L4

知识笔记：

新词：chasm 峡谷；tunnel 打通隧道；flaw 瑕疵；plateau 高原，平稳时期；distinguish 分辨；

词组：extend to 使达到，伸展到；

练习感悟：

今天真的算是有点草率吧，甚至可以算是次日的凌晨。

但是家里来了客人。