商品只能在出示原始收据的情况下退换。

Goods can only be ___exchanged on production of the original receipt.

我能把这件衬衫换个大号的吗？

Could I ___exchange this shirt for a larger size?

我需要换这双鞋，因为它们不合适。

I need to ___exchange these shoes because they don't fit properly.