fix C-h

emacs.el

@@ -185,7 +185,8 @@ return nil if LIB unfound and downloading failed, otherwise the path of LIB."
      (setq drill-instructor-global t)
      (let ((map drill-instructor-key-map))
        (define-key map (kbd "RET") nil)
-       (define-key map (kbd "DEL") nil)))
+       (define-key map (kbd "DEL") nil)
+       (define-key map (kbd "C-h") nil)))
 '(mapc (lambda (key)
         (global-set-key (read-kbd-macro key) 'ignore))
       '("<up>" "<down>" "<right>" "<left>"))