rain check

rain-check的词性：
n.（名词）

1. A ticket stub entitling the holder to admission to a future event if the scheduled event is canceled because of rain.
可继续使用的票根：一种票根，允许持有者如因原定的活动遇雨取消可以参加将来的活动

2. An assurance to a customer that an item on sale that is sold out or out of stock may be purchased later at the sale price.
可现价购买保证：给顾客的一种保证，一种脱销的商品以后不久可以按现价买到

3. A promise that an unaccepted offer will be renewed in the future:
改日可以：一种允诺，目前无法接受的提议将来可以重新提出：

declined the invitation to dinner, but asked for a rain check.
婉言谢绝了吃晚餐的邀请，但请求延期