题目

用右图所示装置检验乙烯时不需要除杂的是乙烯的制备试剂X试剂Y ACH3CH2Br与NaOH乙醇溶液共热H2OKMnO4酸性溶液 BCH3CH2Br与NaOH乙醇溶液共热H2OBr2的CCl4溶液 CCH3CH2OH与浓H2SO4加热至170℃NaOH溶液KMnO4酸性溶液 DCH3CH2OH与浓H2SO4加热至170℃NaOH溶液Br2的CCl4溶液 答案：BChina has been considering raising the retirement age since 2008 to ________ its shrinking workforce and aging society.A．set offB．put offC．bring aboutD．cope with