单选题 Before placing a firm order, we should be glad if you would send us your products on fifteen day's approval. Any of the items unsold at the end of the period and which we decide not to keep as stock, would be returned at our expense. I'm looking forward to hearing from you soon.

【正确答案】在正式下订单之前，如果贵方同意给我们15天的试销期，我们将会感到很高兴。在试销期限结束时，任何未销出而我们又不准备库存的产品将退还给你们，退货费用由我方负担。我期待着早日收到你的回信。

【答案解析】提示：unsold(未销出的)是过去分词作后置定语：which we decide not to keep as stock是定语从句，修饰Any of the items(我们又不准备库存的产品)；at the end of the period意为“在此期限结束时”；at our expense意为“由我方负担”。