A harmonious society is like a symphony orchestra-each person contributes a small sound, but

when ________ with other sounds, it becomes beautiful music.[ ]

A. combining  

B. being combined

C. combined  

D. to be combined

防治乙肝，应从平时做起。下列预防措施哪一项是没有必要的?[ ]

A．注射疫苗                            

B．勤洗手(肥皂加流动水洗手)

C．与乙肝患者的日用品分开使用          

D．与乙肝患者彻底断绝来往