— What made Bill so angry? 

—  _____. His girl friend promised to come at 8:30, but she hasn't come yet. [ ]

A. Having kept waiting

B. Being kept waiting

C. To be kept waiting

D. Being kept waited

有关乳牙龋病的预防，哪一项是正确的（）

A.龋病预防工作，应有家长参与完成

B.出生6个月后，即应诱导幼儿刷牙

C.饮食管理主要是进软甜食后要刷牙

D.氟化亚锡和氟化银可作预防药物使用

E.3岁以后使用含氟牙膏防龋