将方程x2+8x+9=0左边变成完全平方式后,方程是( )
A:(x+4)2=7
B:(x+4)2=25
C:(x+4)2=﹣9
D:(x+4)2=﹣7
李爷爷患上了骨质疏松症,体内可能缺乏( )
—I'm trying to keep my cool because we've been together ________ three years.