美国科学60秒 SSS 2012-10-16_在线英语听力室_免费在线英语听力学习网站

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Pet turtles can be unsanitary. But Chinese soft-shelled turtles really up the ante on distasteful behavior. They perform a variation on urination—through their mouths.

Most land-based vertebrates produce urine to get rid of water-soluble toxic¹ waste, notably² nitrogen-containing urea. But researchers found that Chinese soft-shelled turtles get rid of just six percent of their urea through the kidneys. They also discovered a high concentration of urea in the turtles' saliva³. Which led them to one place: the mouth.

Fish can remove waste through their gills, and these air-breathing turtles have gill-like structures in their mouths. Further research showed that they also have a urea-transporting protein that helps them get rid of it. The findings are in the Journal of Experimental Biology.

When the turtles aren't able to go for long swims, they were seen spending well over an hour with their heads submerged in puddles⁴. Apparently⁵ they were releasing the urea and cleaning out their mouths. And maybe just looking for a little privacy.

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收听单词发音

1 toxic
adj.有毒的，因中毒引起的
参考例句：
The factory had accidentally released a quantity of toxic waste into the sea.这家工厂意外泄漏大量有毒废物到海中。 There is a risk that toxic chemicals might be blasted into the atmosphere.爆炸后有毒化学物质可能会进入大气层。

2 notably
adv.值得注意地，显著地，尤其地，特别地
参考例句：
Many students were absent,notably the monitor.许多学生缺席，特别是连班长也没来。 A notably short,silver-haired man,he plays basketball with his staff several times a week.他个子明显较为矮小，一头银发，每周都会和他的员工一起打几次篮球。

3 saliva
n.唾液，口水
参考例句：
He wiped a dribble of saliva from his chin.他擦掉了下巴上的几滴口水。 Saliva dribbled from the baby's mouth.唾液从婴儿的嘴里流了出来。

4 puddles
n.水坑，（尤指道路上的）雨水坑( puddle的名词复数 )
参考例句：
The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。 The road was filled with puddles from the rain. 雨后路面到处是一坑坑的积水。来自《简明英汉词典》

5 apparently
adv.显然地；表面上，似乎
参考例句：
An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。 He was apparently much surprised at the news.他对那个消息显然感到十分惊异。