1. 监控;监视;监督
    If you monitor something, you regularly check its development or progress, and sometimes comment on it.

    e.g. Officials had not been allowed to monitor the voting...
           以前不允许官员监督投票。
    e.g. You need feedback to monitor progress.
           你需要利用反馈信息来监控进展。

2. 监听(外国无线电广播等)
    If someone monitors radio broadcasts from other countries, they record them or listen carefully to them in order to obtain information.

monitor

    e.g. Peter Murray is in London and has been monitoring reports out of Monrovia.
           彼得·默里一直在伦敦监听来自蒙罗维亚的新闻报道。

3. 监测仪器;监控器
    A monitor is a machine that is used to check or record things, for example processes or substances inside a person's body.

    e.g. The heart monitor shows low levels of consciousness.
           心脏监测器显示患者神志不清。

4. 显示屏;监视器
    A monitor is a screen which is used to display certain kinds of information, for example in airports or television studios.

    e.g. He was watching a game of tennis on a television monitor.
           他在看电视转播的网球赛。

5. 监督员;监控人;核查员
    You can refer to a person who checks that something is done correctly, or that it is fair, as a monitor .

monitor

    e.g. Government monitors will continue to accompany reporters.
           政府监督员将继续陪同记者。
    e.g. ...UN monitors overseeing Namibian independence.
           监督纳米比亚独立情况的联合国核查员