but venturing deep into the cave is very dangerous indeed. 但是深入洞穴必然极度危险
have to survive on whatever washes into the cave from outside. 必须得吃任何从外边冲进洞内的东西
A bottleneck funnels these exiting bats into dense concentrations 当大群蝙蝠密集地通过瓶颈出口时
and using ladders made from forest vines the gatherers climb into the highest reaches of the cave 采集者利用树藤编成的梯子爬到洞穴的最高处
In Borneo, rain has sculptured the limestone into extremely sharp-sided pinnacles. 在婆罗洲 雨水已将石灰岩 雕凿成无比尖削的石塔
They work together to drive shoals of fish into the shallows. 它们一起合作把鱼群赶到浅水区
where one massive tributary, the Rio Negro, flows into the main river. 一条巨大的支流 ——内格罗河在此汇入干流
it empties into the Atlantic Ocean. 亚马逊河汇入了大西洋
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