题目

Who might Mr. Peterson be?A. A new professor. B. A department head. C. A company director. 答案：【答案】C【解析】此题为听力题，解析略。下列物质间的转化不能一步完成的是     A. KNO3→NaNO3      B. Mg→MgO      C. Na2CO3→NaOH      D. H2O→H2