heads-up

1. N-SING If you give someone a heads-up about something that is going to happen, you tell them about it before it happens. 警告; 事先通知[美國英語]

When the airlines decided to enforce these rules without giving anyone a heads-up, it created a lot of problems for travellers. 航空公司在決定執(zhí)行這些規(guī)定時(shí)沒有事先通知任何人，這給旅客帶來了很多麻煩。