________ those who were not listening the first time, I will repeat the question.[ ]

A．To the benefit of  

B．With the benefit of

C．For the benefit of  

D．With the benefit to

霍乱传播中意义最大的传染源是

A．潜伏期带菌者

B．轻型及隐性感染者

C．典型病人

D．重型病人

E．恢复期带菌者