A.通過公式計算B.通過磁羅經(jīng)觀測C.海圖量取D.估算
A.①變大B.②變小C.③不變D.①②都有可能
A.0.8~0.9;0.8~0.9B.0.8~0.9;0.6~0.8C.0.6~0.8;0.6~0.8D.0.6~0.8;0.8~0.9