YSK if you’re still using an old version of Windows, that you can STILL upgrade to Windows 10 for free, legitimately, through Microsoft, and probably should do so before 11 is released.
from /r/YouShouldKnow
如果你还在使用旧版本的Windows，你仍然可以通过微软免费、合法地升级到Windows 10，并且可能应该在11发布前这样做。