草地上有几只鸭子在嘎嘎叫。There were ducks quacking on the lawn.孩子们去河边喂鸭子和天鹅.The children went to feed the ducks and swans.她教起书来像鸭子下水般地轻而易举.She's taken to teaching like a duck to water....
水银的密度比水大得多.Mercury has a much greater density than water.水银的储存量并不丰富,分布也不广泛.Mercury is by no means, abundant or widely distributed.即使在室温下,水银的发挥性也很显著.Mercury is appreciably volatile even at room temperature....