Football is so exciting that _____ people in the world play it.

A. million of                 B. millions of               C. two millions of

牙髓坏死伴发特殊细菌感染(如腐物寄生菌)又称为

A．牙髓坏疽

B．牙髓脓肿

C．牙髓变性

D．牙髓坏死

E．牙髓梗死