已知方程a2x2+(a+2)y2+2ax+a=0表示的曲线是圆,则实数a的值是( )。
﹣1
Oh,Tom!You are too late.
-Sorry. How I wish I had measures Mr.Smith suggested to leave ten minutes earlier! [ ]
A. adapted
B. revised
C. adopted
D. adjusted.
有关鼻腔湿润的主要来源,下列哪项是错的()。
A.毛细血管经上皮细胞渗出液
B.嗅膜下嗅腺分泌液
C.保留呼出气体中的湿润
D.粘膜上皮内杯状细胞的分泌液
E.粘膜上皮内肥大细胞的分泌液