在括号内填上适当的项:(a+b﹣c)(a﹣b+c)=[a+( )][a﹣( )]。
b﹣c,b﹣c
Jack wasn’t saying anything,but the teacher smiled at him ________he had done something very clever.
A.as if
B.in case
C.while
D.though
踝部胫后神经阻滞术的适应证包括()。
A.足底部疼痛
B.足内侧缘、足踇趾的皮肤疼痛
C.足背第1、2趾相邻侧疼痛
D.足背及足趾相邻侧面疼痛
E.足跖前内侧疼痛