A:(x+2)(x﹣2)=x2﹣4
B:x2﹣4=(x+2)(x﹣2)
C:x2﹣4+3x=(x+2)(x﹣2)+3x
D:x2﹣1=x(x﹣ 1x )
6×8=____ 2×8=____ 8×8=____
The boy is ____. Today is his ____birthday.
下列有关阿佛加德罗常数(NA)的说法错误的是( )