back·up
noun/ˈbækʌp/
/ˈbækʌp/
[uncountable, countable]- extra help or support that you can get if necessary
增援；后援 - The police had backup from the army.
警方得到了军方的增援。 - We can use him as a backup if one of the other players drops out.
如果有参赛者退出，我们可以用他作为替补。 - The hospital has a backup power supply.
这家医院有备用电源。
- The police had backup from the army.
- (computing) a copy of a file, etc. that can be used if the original is lost or damaged
（文件等的）备份 - Always make a backup of your work.
所有文件都须备份。 - a backup copy
备份文件
- Always make a backup of your work.