1. He tried to undo the knot by picking at it with his fingers. 他用手指不停地扯，想把绳结解开。
2. The knot was fastened in such a way that it was impossible to undo. 那个结系死了，没法解开。
3. Oh, do let me help to undo it! 哦，让我帮你解开它吧！
4. Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original. 然后，如果我们想要撤销一些糟糕的修复尝试，我们可以决定使用什么样的方法来移除它们，以溶解油漆并展现其原始面貌。
5. I managed secretly to undo a corner of the parcel. 我设法偷偷地打开包裹的一角。
