Not only should you get used ______ under difficult conditions but you also you pay more attention ______ your work well.

A．to work, to do

B．to working, to doing

C．to work, to doing

D．to working, to do

空腹病人，声像图上胆囊不能显示的常见原因是什么（）

A.慢性胆囊炎胆囊萎缩

B.胆汁淤积

C.不活动的结石

D.在超声检查前使用了X线口服造影剂

E.胆囊占位