单项选择题
A.4200m/s B.4400m/s C.4600m/s D.4800m/s
A.128kPa B.167kPa C.251kPa D.392kPa
A.10.5m,200m/s B.13.5m,225m/s C.15.0m,235m/s D.15.0m,250m/s