以下物质不能由两种单质直接反应得到的是 [ ]
A. SO2
B. SO3
C. MgO
D. Na2O2
答案：B
什么叫mBnB码？
_____, the excited crowds in the square suddenly became so quiet. It's still puzzling. [ ]
A. Personally
B. Naturally
C. Somehow
D. Anyway
