A:氢化物稳定性增强:HF、H2O、NH3
B:酸性减弱:HClO4、HBrO4、HIO4
C:还原性增强:A1、Mg、Na
D:非金属性减弱:Cl、S、P
已知实数a、b满足(a2﹣b2)2﹣2(a2﹣b2)=8,则a2﹣b2的值为( )
Tim:Yes,I have an e-friend in the US.His name is David.He is 15 years old.He is a____student.