—You’ve made great progress in your English study, haven’t you?

—Yes, but much        .

A．remains to do

B．is remained to do

C．remains to be done

D．is remained to be done

经皮肾镜采用的冲洗液是（）

A.5%甘露醇

B.0.9%氯化钠溶液

C.灭菌蒸馏水

D.1.5%甘氨酸

E.稀释造影剂