完成句子. Acid rain one of the most serious global environmental problems．
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完成句子。
Acid rain ________ ________ ________(被认为是)one of the most serious global environmental problems．
试题答案
答案：is,recognized,as
完成句子。
Acid rain ________ ________ ________(被认为是)one of the most serious global environmental problems．
答案：is,recognized,as