你可曾注意过这样的广告：“六周之内保你学会一门外语，否则退款。”
Have you ever noticed advertisements which say: "learn a foreign language in 6 weeks, or your money back!"
为什么没有人告诉我们除非旅行社能从预订的酒店、旅游巴士公司等地方收回乘客的费用，否则旅行社不能退款？
Why hadn't anyone advised us that the travel agency can't refund your money unless the tour operator can get the passengers' fees back from the reserved hotels, the tour bus company and so on?
因此，我希望可以换一个相机，否则我要求退款。
Therefore, I wish to exchange it for another camera or declare a refund.
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