The marshy land at the mouth of the Neva River hardly lent itself to habitation.涅瓦河河口的沼泽地不适合居住。Sand had accumulated at the mouth of the river and formed a bank which boats could not pass.沙子聚集在河口，形成了一个沙洲，导致船只无法通过。Shanghai plants at the mouth of Changjiang River.上海位于长江口。