Of course not. Just swipe the A card 2000 as you said, and then take the money out of the B card and return it to the A card before the interest-free period. It's true that A card doesn't charge interest, but you have to charge a handling fee for B card to withdraw money. After the repayment date of card B, it is very uneconomical for you to withdraw money from card A and return it to card B, man.