自然界最简单的有机物是( )
A.CO
B.C2H5OH
C.CO2
D.CH4
答案:D
Let me_______ you what's going on. [ ]
A. tells
B. telling
C. tell
D. told
在Al2(SO4)3、K2SO4和明矾的混和溶液中,如果c(SO42-)等于0.2mol/L,当加入等体积的0.2mol/L的KOH溶液时,生成的沉淀恰好溶解,则原混和液中K+的物质的浓度为( )
A.0.2mol/L
B.0.25mol/L
C.0.45mol/L
D.0.225mol/L