______ metals are good conductors, silver ______ the best conductor of all.

A．Almost, being

B．Almost all, being

C．Almost, is 　

D．Almost all, to be

关于免疫缺陷病的治疗，错误的是

A．抗菌药物以杀菌性为佳

B．抗生素剂量和疗程应大

C．选择性IgA缺乏症禁忌输血

D．严重细胞免疫缺陷的病人，最好输新鲜血

E．细胞免疫缺陷者禁忌接种活疫苗