做mount掛載時，修改了  /etc/fstab 檔案，導致Centos7重啟時出現如下圖所示錯誤：

Welcome to emergency  mode! After logging in, type "journalctl -xb" to view

system logs,"systemctl  reboot" to reboot ,"systemctl default" or ^D

to try again to boot into default mode.

Give root password for maintenance

(or type Control-D to continue):

輸如root許可權密碼， vi /etc/fstab 將自己多配置的一行內容刪除，wq儲存,之後reboot重啟虛擬機器，就恢復正常了。