Solve the error of dual system installation: the grub-efi-amd64-signed package failed to install into /target/.

When Windows 10 installed Ubuntu16.04 and dual systems, the grub-amd64- package could not be loaded into target. There were three steps to solve the problem.
1, choose to boot from the storage disk and is legacy only.
2, the startup disk will have two options in the startup TAB, one with the UEFI option, the other without, select no UEFI startup.
3, when assigning the boot location, do not assign the /boot option, for reasons shown here.

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