墨尔本文波雅思PTE的小编发现，PTE的re-tell lecture/ summarize spoken text很多同学听不懂是因为背景知识完全不知道，还有一些专业词汇不认识，今天小编给大家做一个科学知识科普专题1。帮助大家能够在没有听懂的情况下也能“蒙混过关”。
小编上次试了次潜水（在不会游泳的情况下），本来满心期待可以看到这样的珊瑚：
或者是这样的：
可惜最后只潜了3米，看到的都是这些个。。。
哎，桑心！
最近看到一则报道，更桑心！
The most devastating coral bleaching event the world has ever seen is underway on the Great Barrier Reef. Australia’s preeminent scientists, conservationists and tourism operators warn this event points to the end of coral reefs worldwide unless change is made.
devastating: if you describe something as devastating, you are emphasizing that it is very harmful or damaging, e.g. Affairs do have a devastating effect on marriages.毁灭性的
underway: if something is underway, it is happening now. e.g. Economic recovery is already underway.在进行中
preeminent: means more important or powerful than all others, e.g. He was the preeminent scientist of his day.卓越的
珊瑚们都开始被漂白，如果情况再严重下去，也就意味着以后你可能看到的是这样的珊瑚：
Stressed coral turns an unnatural shade before it is bleached completely.
亦或者是这样的，怎么像一排排。。。，好惊悚的赶脚
Bleached coral in Papua New Guinea.
What is coral bleaching?
到底什么是Coral bleaching呢？科普时间到
Coral hosts tiny algae/’ælɡədʒiː/ in its tissues called zooxanthellae /zəuəuzæn’θeli:/ that produce its food as well as its colour.
珊瑚在它的组织内聚集了极小的藻类（虫黄藻），虫黄藻能够制造珊瑚的食物及颜色。
When waters become too hot or cold, the coral becomes stressed and its metabolism /mɪ’tæbəlɪz(ə)m/ and reproductive system break down.
当水温变得太热或者太冷的时候，珊瑚逐渐收缩，其新陈代谢和再生系统发生故障。
At this point, it cannot process the oxygen created by the zooxanthellae, so it expels them.
这个时候，珊瑚不能加工虫黄藻产生的氧气，就开始驱逐这些虫黄藻。
If the temperature returns to normal, these tiny creatures can re-enter the tissues, or if most but not all algae have been expelled, the remaining few can keep the coral alive.
如果水温回到正常，这些微小的生物能够重新进入珊瑚的组织，或者如果之前大部分但不是所有的藻类都被驱逐出去，一些残留下来的藻类也能够使珊瑚活下去。
If the temperatures remain extreme and the sun continues shining, the coral dies.
但如果水温一直过热或者过冷，太阳持续照射，珊瑚就会死掉。
专家呼吁大家开始采取行动保护珊瑚
“Coral bleaching is the most visible example of climate change,” World Wildlife Fund’s Rick Leck said.
“Coral reefs are amazing in their ability to recover if you take away the threats that are causing their degradation,” Leck said.
“If we take action on renewable energy, if we reduce the pollution that’s flowing to the reef and we invest in those systems we know can work, then the reef can recover.
“It may take years, it may take decades but it will recover and that’s what we need to be working towards.”
P.S. 最后两张图大家可以用来练习PTE Decribe Image！！！
墨尔本文波雅思PTE原创出品
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