A: I'd like to send this by air mail, please.
甲:我想要用航空邮寄这个,麻烦你。
B: Is it a birthday card?
乙:那是生日贺卡吗?
A: Yes. Why do you ask?
甲:是的。你为什么这样问?
B: Cards are cheaper than letters.
乙:卡片比信件要来得便宜。
A: Oh! Really?
甲:哦!真得吗?
B: You can't seal the envelope, though.
乙:不过您不能把信封封起来。
A: OK. How much for the stamps?
甲:好吧。我要贴多少钱的邮票?
B: Two dollars.
乙:2 美元。