那張留到下次的票券
這一支就是卡片本身，只是拿在不同的地方：球場門口，或商店櫃台。
noun · C1
A ticket given to people at a baseball game or another outdoor event that is stopped or called off by rain, letting them come to a later one without paying again.
雨天補發票
核心畫面
One way to hold it: you paid, you turned up, and then the rain took the thing away before you got it. Someone hands you a small piece of card. The card says the deal is not gone — it is waiting for you on another day. Every use of this phrase is that card, moved to a new place: to a shop shelf that ran empty, or to a Friday night when you simply cannot come.
可以想成：你付了錢、人也到了，結果一場雨把整件事帶走了。有人遞給你一張小卡片。卡片的意思是：這筆交易沒有作廢，它在另…更多收起
可以想成：你付了錢、人也到了，結果一場雨把整件事帶走了。有人遞給你一張小卡片。卡片的意思是：這筆交易沒有作廢，它在另一天等你。這個說法的每一種用法，都是這張卡片被搬到別的地方——搬到賣空的貨架上，或是搬到一個你怎麼樣都到不了的星期五晚上。From the word’s history
Wiktionary dates it to US baseball in 1877: from at least 1870 clubs reissued tickets when a game was rained off, and those reissued tickets were called rain checks; the figurative use follows from 1896.
Wiktionary 把它追到一八七七年的美國棒球：至少從一八七零年代起，比賽因雨延期時球團會補發球票，那種票就叫 rain check；比喻用法從一八九六年開始出現。
Wiktionary entry for “rain check” (evidence packet, source_ref kaikki:3f6f69a190036ae4:1395480317)
Two branches
把邀約留到下一次
卡片這次不是紙做的，而是一句話：今天來不了，但這份邀請還算數。
noun · B2
Used to say no to an invitation now while asking to accept it another time, so the offer stays open instead of ending.
改天再約