题目

既是我国特产的淡水爬行类动物,又属国家一级保护动物的是 A.白鳍豚              B.中华鲟              C.大鲵            D.扬子鳄 答案：DMany people believe we are heading for environment disaster ________ we basically change the way we live. [     ]A. if  B. butC. unless  D. once