Centos7.3 was used well yesterday, but the boot prompt today is as follows (as shown in the figure):
welcome to emergency mode! after logging in ，type “journalctl -xb” to view system logs，“systemctl reboot” to reboot ，“systemctl default” to try again to boot into default mode。
give root password for maintenance
（？？ Control-D？？？） ：

After checking, it is because I wrote the CD in/etc/fstab to mount automatically, but the boot is not successful.

Solution: there is a problem with the fstab file that is automatically mounted, you can directly enter the password in this interface, and then delete the one you added, and restart OK
1: log in to the root garbled code, and also enter the password
2: VIM/etc/fstab, check the disk mounting information
3: comment out the content you added, and delete it if you are sure you are not using it
4: restart OK.

This error is mostly due to the error in the/etc/fstab file. Pay attention to whether the external hard disk, memory or network commons are loaded and not loaded during restart.