将固体NH4I置于密闭容器中,在某温度下发生下列反应:NH4I(s)NH3(g)+HI(g)、2HI(g)H2(g)+I2(g),当反应达到平衡时,c(H2)=0.5mol/L,c(HI)=4mol/L,则NH3的浓度为 ()。A.3.5mol/L B.4mol/LC.4.5mol/L D.5mol/L 答案:D【试题分析】 Have you ___________ where to go for your honeymoon? A. made up your minds B. changed your minds C. kept in mind D. fixed your minds