1.

1. We must crusade for world peace.
    我们必须为世界和平而奋斗。

1. (长期坚定不移的)斗争，运动
    A crusade is a long and determined attempt to achieve something for a cause that you feel strongly about.

    e.g. Footballers launched an unprecedented crusade against racism on the terraces...
           足球运动员们对阶梯看台上的种族歧视发起了一场空前的运动。
    e.g. He made it his crusade to teach children to love books.
           他把教孩子们热爱读书当做自己的使命。

2. 长期坚定不移地奋斗
    If you crusade for a particular cause, you make a long and determined effort to achieve something for it.

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    e.g. ...a newspaper that has crusaded against the country''s cocaine traffickers.
           坚决抨击该国可卡因毒贩的报纸
    e.g. ...an adopted boy whose cause is taken up by a crusading lawyer.
           由一位执著坚定的律师受理其诉讼案件的被收养男孩

3. (发生于11世纪至13世纪的)十字军东征
    The Crusades were the wars that were fought by Christians in Palestine against the Muslims during the eleventh, twelfth, and thirteenth centuries.

1. a series of actions advancing a principle or tending toward a particular end

    e.g. he supported populist campaigns
           they worked in the cause of world peace
           the team was ready for a drive toward the pennant
           the movement to end slavery
           contributed to the war effort

    Synonym: campaigncausedrivemovementeffort

1. go on a crusade
    fight a holy war

2. exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person
    be an advocate for

    e.g. The liberal party pushed for reforms
           She is crusading for women''s rights
           The Dean is pushing for his favorite candidate

    Synonym: fightpresscampaignpushagitate