题型:单项选择题 The house _____ we lived in three years ago is very old.A. what B. which C. where D. when 查看答案
题型:单项选择题 已知某物质X在常温下是一种易燃性液体,其在空气中燃烧的化学方程式可表示为:X+3O2 点燃 . 2CO2+3H2O,则X的化学式为( )A.CHOB.CH4C.C2H6OD.C2H6 查看答案