下列可称为京剧表演艺术家的是______． A．程长庚和谭鑫培 B．任伯年和谭鑫培

在进行x线片检查前，应该进行的处理

A．行简单的外固定及局部包扎

B．行气压止血带止血

C．急送手术室

D．石膏固定

E．跟骨结节牵引

My pen pal said he would write to me, but I ______ any letters from him so far. [ ]

A. won't receive

B. haven't received

C. hadn't received

D. didn't receive

企业将应收债权出售给银行等金融机构时，均应确认相关损益。( )

设函数f(x)=arcsinx，则f'(x)等于( )．

尖轨左右股可以互换。