They had to edge their way along this, sometimes wading across shallowstreams, or swimming across deep pools. Suddenly they came to a waterfall whichdropped into an underground lake at the bottom of the cave. They plunged into thelake, and after loading their gear on an inflatable rubber dinghy, let the current carrythem to the other side. To protect themselves from the icy water, they had to wearspecial rubber suits. At the far end of the lake, they came to huge piles of rubble whichhad been washed up by the water. In this part of the cave, they could hear an insistentbooming sound which they found was caused by a small water-spout shooting downinto a pool from the roof of the cave. Squeezing through a cleft in the rocks, thepotholers arrived at an enormous cavern, the size of a huge concert hall.

　　20.They had to edge their way along this, sometimes wading across shallow streams,or swimming across deep pools.

　　他们不得不侧着身子往前走，有时过浅溪，有时游过深潭。

　　21.Suddenly they came to a waterfall which dropped into an underground lake at thebottom of the cave.

　　突然，他们来到一道瀑布前，那瀑布奔泻而下，注入洞底一处地下湖里。

　　22.They plunged into the lake, and after loading their gear on an inflatable rubberdinghy, let the current carry them to the other side.

　　他们跳入湖中，把各种器具装上一只充气的橡皮艇，听任水流将他们带往对岸。

　　23.To protect themselves from the icy water, they had to wear special rubber suits.

　　湖水冰冷刺骨，他们必须穿上一种特制的橡皮服以保护自己。

　　语言点:icy water表示“冰水”。

　　24.At the far end of the lake, they came to huge piles of rubble which had been washedup by the water.

　　在湖的尽头，他们见到一大堆一大堆由湖水冲刷上岸的碎石。

　　25.In this part of the cave, they could hear an insistent booming sound which theyfound was caused by a small water-spout shooting down into a pool from the roof ofthe cave.

　　在这儿，他们可以听见一种连续不断的轰鸣声。后来他们发现这是由山洞顶部的一个小孔里喷出的水柱跌落到水潭中发出的声音。

　　26.Squeezing through a cleft in the rocks, the potholers arrived at an enormouscavern, the size of a huge concert hall.

　　洞穴探险者从岩石缝里挤身过去，来到一个巨大的洞里，其大小相当于一个音乐厅。

　　语言点:句子结构分析: the size of a huge concert hall是cavern的同位语。