短语词组短语buoyance module 浮力组件negative buoyance 负浮力external buoyance 外部浮力low buoyance 小储备浮力reserve buoyance 储备浮力full buoyance 巡航状态net buoyance 净浮力buoyance flux 浮力通量intact buoyance 完整浮力 返回 buoyance