极地水域的成层性是微弱而暂时的.Stratification in polar waters normally is weak and transient.潜水:潜入一片水域的底部; 潜入水中.To go toward the bottom of a body of water ; submerge.她不洗衣和水域的花园里偶尔一些.She does some of the laundry and waters the garden oc...