A.1.36g/cm3 B.1.40g/cm3 C.1.34g/cm3 D.1.42g/cm3
A.不用壓井 B.要降低密度 C.要提高密度 D.要壓井
A.1.35g/cm3 B.1.50g/cm3 C.1.60g/cm3 D.1.70g/cm3