这个命令把文件恢复到以前的状态，见清单7。

This command restores the file to its previous state, as shown in Listing 7.

youdao

不能使用它，因为文件已被保存；此处没有UNDO命令，因此，程序员需要恢复备份或重新输入。

You can't, because the file was saved; there is no UNDO here, so the programmer would need to either recover the backup copy or retype it.

youdao

在辅助系统上，复制文件或挂载磁带(由LTAPE dev指定)，并用以下命令执行物理恢复。

On the secondary system, copy the files or mount the tape (as assigned by LTAPEDEV) and perform a physical restore with the following command.

youdao