1. （提议、原则、观点）占上风，占优势，获胜，被接受
    If a proposal, principle, or opinion prevails, it gains influence or is accepted, often after a struggle or argument.

    e.g. We hope that common sense would prevail...
           我们希望情理会占上风。
    e.g. Rick still believes that justice will prevail...
           里克仍然相信正义会得以伸张。

2. （情形、态度、风俗）盛行，流行，普遍
    If a situation, attitude, or custom prevails in a particular place at a particular time, it is normal or most common in that place at that time.

prevail的意思

    e.g. A similar situation prevails in America...
           相似的情况在美国随处可见。
    e.g. ...the confusion which had prevailed at the time of the revolution...
           在革命期间普遍存在的混乱

3. （在战斗、竞赛、争论中）获胜，取胜
    If one side in a battle, contest, or dispute prevails, it wins.

    e.g. He appears to have the votes he needs to prevail...
           他似乎已经获得了取胜所需的选票。
    e.g. I do hope he will prevail over the rebels.
           我确实希望他能战胜叛乱者。

4. 劝服；说服
    If you prevail upon someone to do something, you succeed in persuading them to do it.

    e.g. We must, each of us, prevail upon our congressman to act...
           我们每一个人都必须说服我们各自的国会议员采取行动。
    e.g. Do you think she could be prevailed upon to do those things?
           你觉得有可能说服她去做那些事情吗？