Why do you need to install grub?
Isn't grub installed at OS installation?
Not sure, but it seems grub was not launched by default, because the first option I have was: instead of grub's own boot interface.
And why choose sdb instead of sda in your grub-install command?
Because windows is installed in sda, and many important data stored there.
Thanks for reply.
OMG, OMG, from the picture above(
[C] GRUB Commandline), it seems grub is launched by default! so silly I am
The worst news is I have no USB flash card available now.@akii