I am from Argentina, and am currently in Hanoi for 2 more days. I need to go to China for just one day after Hanoi, but I do not have the Tourist VISA to get into China yet. Can I get the CHina Tourist VISA at the airport in Hanoi before I fly to China?

I was in China for 4 months before coming here, and I entered China with a Single Entry student VISA. BUt since it was single entry, I already used it.