南极冰川下有个湖，证据显示湖里有complex organisims。
三个理论支持：1.冰块样本的RNA分析，有complex organism的RNA 2. 一种常常在火山口生活的细菌也存在湖里，因此说明有火山提供energy source 3.一种湖里有寄生细菌，因此湖里有更高级的host orginisms.
三个反对点： 1.冰块被不干净的钻探设备污染 2.湖里有通道和海洋连接，因此这些细菌可能来自海里 3. 寄生菌有两种生存方式，要么寄生在host上，要么live independently
None of the three hypotheses proposed in the reading can effectively prove there are complex organisms in the lake under the glaciers in Antarctic.
Firstly, from the perspective of the unknown RNA sample in the iceberg, the professor states his doubt, because according to the lecture, the sample taken from the iceberg may have been polluted by the equipment in the exploration and is not effective enough.
Moreover, judging from the possible energy source--bacteria, the professor holds a different view, as the lecture further illustrates that the bacteria may have floated from nearby sea, as the lake is proven to have connected the nearby sea, where the bacteria active along the crater are sufficient.
Last but not least, on the point of parasite, the professor never fails to express his concern, because in terms of the listening, the parasite could live either on host organisms or independently, and this is not necessarily to prove the existence of complex organisms. (160 words)
