In an hour or two the sun will have burnt it off 1~2小时后 太阳将使它们蒸发
but cave explorers were soon to make an even more astonishing discovery. 但是洞穴探险家们 很快又有了更惊人的发现
that an early warning system is essential. 所以即时预警设备是最重要的
produce an infinite variety of forms, but all are created by the same process - 造就了千姿百态的溶洞地形 但它们的形成过程都是一样的
an inner world where only the most adventurous dare to go. 一个只有最勇敢者 才敢涉足的地底世界
and floods an area the size of England. 洪水淹没的地区相当于一个英格兰
Baikal seems more like an ocean than a lake. 贝加尔湖看起来 更像是海洋 而不是湖泊
For five months of the year it's sealed by an ice sheet over a metre thick. 每年中总有5个月 湖面被1米厚的冰层覆盖
Malawi may look like an inland sea, 马拉维湖看起来像大海一样辽阔
The floor of Lake Malawi drops 700 metres into an abyss. 马拉维湖底是一个深达700多米的深渊