When _______, he didn't want to tell us _______ he had done to the old blind man.  [ ]

A. being asked, that what      

B. asking, all that  

C. asked, all that            

D. to be asked, all which

减少和排除散射线的方法，错误的是

A．缩小照射野

B．利用X线束限制器

C．空气间隙法排除散射线

D．用缩光器抑制焦点外X线

E．选择较高管电压可减少散射线