题目

鉴别已烯、苯、甲苯、溴乙烷四种无色液体，必须用到的试剂有A．KMnO4(H+)溶液    B．NaOH溶液    C．溴水     D．AgNO3溶液  答案：AC解析: Having mastered the technology of manned spacecraft, China became the third country in theworld ______ manned spaceflight independently. [      ]A. to develop     B. developing     C. developed     D. develop