听力原文：W: How do you pay for your purchases with a credit card?M: Usually I sign a sales slip in the presence of the seller, and the signature is then compared to the signature on the card.Q: Where should the man sign when he pays for his goods with a credi

听力原文：W: How do you pay for your purchases with a credit card?

M: Usually I sign a sales slip in the presence of the seller, and the signature is then compared to the signature on the card.

Q: Where should the man sign when he pays for his goods with a credit card?

(20)

A．On his card.

B．On the goods.

C．On a sales slip.

D．On the invoice.