下列物质中,既含有离子键又含有非极性共价键的是( )
A:HClO
B:Ba(OH)2
C:Na2O2
D:Ar
–What do you think of this ________?–I love it. I learned a lot about Steve Jobs after reading it.
山脉是地形的“骨架”,对图中①﹣④地形区的判断正确的是( )