| n 用法:
1 [U] support; reserve 支持; 支援; 後备:
The police had military back-up. 警方有军队作後盾. *
[attrib 作定语] back-up services 善後服务 *
the back-up team of a racing driver 赛车手的後勤队. 用法:
2 [U, C] (computing 计) (making a) copy of a file, program, etc for use in case the original is lost or damaged （制作）（文件、程序等的）复制件（以备原件丢失或损坏时使用）:
[attrib 作定语] a back-up disc 复制件磁盘. |