介绍： 1.marked downIf something is ‘marked down’ then it has a discounted price. 折扣价Example: ‘Are these shoes marked down?’2.nail downWhen you ‘nail down’ something then you confirm it.做决定、确认Example: ‘I would like to nail down the dates for the conference as soon as we can.’3.keep on your toesTo ‘keep on your toes’ means to stay alert and stay aware of everything that is going on around you.机警地观察四周Example: ‘Keep on your toes, the red team are on their way now.’4.own upWhen you ‘own up’ to something then you confess and admit something, you take responsibility for it.承认某事，并为此担责Eg: ‘I don’t know who broke my glasses, but someone needs to own up now. ’ 5.slip of the tongueA ‘slip of the tongue’ is when you say something that you didn’t mean to say. 说漏嘴Eg: ‘Be careful, one slip of the tongue and they'll know all our plans.’结尾音乐：《Thirty》- Robby Hecht