英汉词典

1. 解开；松开；打开
    If you undo something that is closed, tied, or held together, or if you undo the thing holding it, you loosen or remove the thing holding it.

    e.g. I managed secretly to undo a corner of the parcel...
           我悄悄地设法解开了包裹的一角。
    e.g. I undid the bottom two buttons of my yellow and grey shirt...
           我解开了自己黄灰相间的衬衫上最下面的两个纽扣。

2. 撤销；抵消；消除
    To undo something that has been done means to reverse its effect.

    e.g. A heavy-handed approach from the police could undo that good impression...
           警方采取高压手段可能会毁掉之前留下的好印象。
    e.g. She knew it would be difficult to undo the damage that had been done...
           她知道想要消除已经造成的损害是很难的。

3. 破坏；毁掉
    If a person, organization, or plan is undone by something, that thing causes their failure.

    e.g. They were undone by a goal from John Barnes...
           约翰·巴恩斯的一粒进球使他们落败。
    e.g. Macbeth is the story of a Scottish soldier who becomes king but is undone by his own ambition.
           《麦克白》讲述的是一个苏格兰士兵当上了国王，却毁于自己的野心。

4. see also: undoing;undone