rain check
noun /ˈreɪn tʃek/
  /ˈreɪn tʃek/
(especially North American English)Idioms - a ticket that can be used later if a game, show, etc. is cancelled because of rain(比赛、演出等因雨取消时)可延期使用的票 
Idioms 
take a rain check (on something) 
- (especially North American English, informal) to refuse an offer or invitation but say that you might accept it later(婉辞邀请)下次吧,以后再说 - ‘Are you coming for a drink?’ ‘Can I take a rain check?—I must get this finished tonight.’“你来喝一杯吧?” “下次吧,好吗?今晚我得把这项工作做完。” 
 
- ‘Are you coming for a drink?’ ‘Can I take a rain check?—I must get this finished tonight.’