Thanks. But.....

Thanks ImmCanada.
My old DS form is to end of April. I plan to leave USA Jan 12. Hence, there is no enough time to extent my DS form. I plan to apply my enter visa at end of Jan in China. It should not have problem to get the enter visa. I only worried whether I can smoothly extend my DS form when I come back USA at middle of Feb, because I just enter USA using a new J1 enter visa (although the DS form is old).