He has failed several times,        he never gives up.

A. if                      B. so                  C. but

目前特发性血小板减少性紫癜治疗的最常用方法是()

A．肾上腺皮质激素

B．输血或血小板

C．脾切除

D．免疫抑制疗法

E．大剂量丙种球蛋白静脉注射