单项选择题
A.20~30mmHg B.25~30mmHg C.30~50mmHg D.40~60mmHg E.50~70mmHg
A.2~7cmB.3~8cmC.4~9cmD.5~10cmE.3~6cm
A.4~6cm B.6~7cm C.7~8cm D.7~9cm E.9~10cm