剑桥词典very unlikely to fail 萬無一失的，萬全的 a fail-safe plan 萬無一失的計劃 If something is fail-safe, it has been designed so that if one part of it does not work , the whole thing does not become dangerous . 可自動防止故障危害的；有自動保險裝置的 a fail-safe device 故障保護裝置 返回 fail-safe