顾客有权在一段时间内退货，如果期限已过，也可以换货。 段中be entitled to表示"有权利做某事"，refund表示"退款"。

When a customer is not satisfied with a product, he is entitled to return it to the store and get refunded during a certain period of time.

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一锤子买卖意味着你不能退货或是换货。

A final sale means you cannot return or exchange the gift.

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请保存好收据。如果你碰巧需要换货或退货，它就用得着了。

Please keep the receipt well. If you happen to need to exchange or refund, it is required.

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