晶面族
参考答案:对称关系(原子排列和分布,面间距)相同的各组等同晶面,称一个晶面族,用{hkl}表示。
解方程:
(1)2x2=5x (2)m2+3m-1=0 (3)9(x+1)2-(x-2)2=0
Blackmail is something that should never be _________, but it's easier said than done. [ ]
A. given out
B. given away
C. given up
D. given in to