. Many experts agree that once these treasures are to the air great harm will be done to

问题补充：

. Many experts agree that once these treasures are to the air, great harm will be done to them. So they think it better not to unearth the treasures.

A. exposed

B. threatened

C. constructed

D. conserved

答案：

(答案→)A. exposed

B. threatened

C. constructed

D. conserved

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