Tommy is ____ only child in the family, so his parents make ____ fuss of him.

A．an, \

B．\ , the

C．\ , a

D．the , a

破骨细胞的鉴定标准为：①合成基质偶氮显色法显红色；②抗酒石酸磷酸酶染色阳性；③鲎试验阳性；④细胞表面降钙素受体阳性；⑤可以在骨表面形成骨吸收陷窝（）

A.①⑤

B.①②⑤

C.③⑤

D.②④⑤

E.②③⑤