1 . 用新材料来做这些东西要花费大量的能源，因此，只要有可能，就买那些用回收材料制成的物品吧！
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2 . The Great Wall __________（build） by ancient Chinese people is regarded as one of the few wonders of the world. （用单词适当形式填空）

3 . Don’t use words, expressions or phrases _____ only to people with specific knowledge.

A．being known	B．having been known
C．to be known	D．known