题目内容：
第50题___________
A．Some people might want to learn some of these songs by hearts. B．Papua New Guinea is an extremely rich source of different language, but more than 100of them are in danger of extinction ( 灭绝 ) .
C．However, he was a frequent visitor to the Catawba reservation in South Carcinoma where he learned the language.
D．These languages don't have many native speakers.
E．For the rest of us, when a language dies, we lose the possibility of a unique way of seeing and describing the world.
F．As these languages become more powerful, their use as tools of business and culture increase.
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