The you have to wait in the border office for a while

Then your case is nearly the same as that of my friend. Seems you have to wait in the border office building for them to check your record in the computer. Then you may get in the U.S.

And, if you apply for visa in Canada, if you fail, then you have to go back to China to reapply. You cannot use I-94 to get in U.S anymore.