By Jon Stewart, Science Desk, BBC

媒体英语会带大家一起学习BBC撰稿人在报道世界大事时常用到的单词和短语。

Background:最近，科学家们称马达加斯加岛上的独有动物的祖先，当年是乘坐天然的"木筏"来到了这座位于印度洋的岛屿上。马达加斯加岛位于非洲东海岸300英里处，是世界上少有的生物多种类岛屿。它拥有很多全球其他地方找不到的生物种类，如哺乳类动物还有很多植物。

Madagascar's uniquelemurs, flying foxes, and mongooses first started to appear about 60 million years ago, but it's been separated from the mainland, and isolated, for at least 100 million years.

The mystery has been, how did they get there, and why are there no giraffes, elephants and big cats?

Professor Matthew Huber from Perdue University in the US:

"The mammals that appear on Madagascar today may have come over on rafts, and by rafts what we mean are trees that may have fallen into a river and been swept out to sea or a large floating mass of matted vegetation that broke off the coast and headed out to sea."

The ocean currents today go the wrong way - from Madagascar to mainland Africa, but Professor Huber used a climate model - the same type we use to predict the future, and effectively ran it backwards to look at the distant past.

He found that the ocean currents used to go the other way, and were strong enough that the animals would have reached the island without dying of thirst.

• mystery [´mistəri]   n.神秘；秘密；故弄玄虚   (初中英语单词)
• climate [´klaimit]   n.气候；特殊气候地带   (初中英语单词)
• thirst [θə:st]   n.渴，口渴；渴望   (初中英语单词)
• unique [ju:´ni:k]   a.唯一的 n.独一无二   (高中英语单词)
• predict [pri´dikt]   v.预言；预告；预示   (高中英语单词)
• mainland [´meinlənd]   n.大陆；本土   (英语四级单词)
• vegetation [,vedʒi´teiʃən]   n.植物；生长   (英语四级单词)
• effectively [i´fektivli]   ad.有效地   (英语六级单词)
• backwards [´bækwədz]   ad.向后 a.向后的   (英语六级单词)