什么是 undo?To reverse or erase; annul: impossible to undo the suffering caused by the war. To untie, disassemble, or loosen: undo a shoelace. To open (a parcel, for example); unwrap.To cause the ruin or downfall of; destroy.To throw into confusion; unsettle.Obsolete To solve or interpret; unravel.To come open or unfastened.