A.密度;p;kg/m3B.重度;γ;N/m3C.密度;γ;kg/m3D.密度;p;N/m3
A.出發(fā)點(diǎn)B.維持點(diǎn)C.立足點(diǎn)D.基礎(chǔ)點(diǎn)
A.經(jīng)濟(jì)B.安全C.發(fā)展D.主權(quán)