题目

Was it six years ago, when he came to China for the first time, _____ he began to learn Chinese? A．where   B．how          C which        D．that 答案：D下列反应中，不属于氧化还原反应的是（  ）。 A．2CO+O2 2CO2         B．CH4+2O2 CO2+2H2O C．2KClO32KCl+3O2↑      D．2Fe(OH)3Fe2O3 +3H2O