单项选择题
A.胸骨左缘区 B.心尖区 C.剑下区 D.胸骨上凹 E.胸骨右缘区
A.25% B.50% C.70% D.75% E.90%
A.5%~10% B.10%~15% C.15%~20% D.20%~25% E.25%~46%