立位片上，腹部游离气体的典型影像为（）
A.球形
B.不规则形
C.新月形
D.半球形，有"气液面"
E.与胸腔间距大于15mm
参考答案：C
容器的开孔补强圈应在压力试验之后通入0.4～0.5Mpa的压缩空气检查焊接接头质量。
A client who recently had a cerebrovascular accident requires a cane to ambulate. When teaching about cane use, the rationale for holding a cane on the uninvolved side is to
A．prevent leaning.
B．distribute weight away from the involved side.
C．maintain stride length.
D．prevent edema.
