you need only do something/all you need do is ...British EnglishBrENEED used when saying that you only have to do something in order to do something else 你只需要做某事/你所要做的只是… We need only look at the building to see how much money it will take to repair. 我们只要看一下那栋楼，就知道要花多少钱维修。
All we need do is threaten them. 我们只需要威胁他们一下。
→ you need only do something/all you need do is ... at need1(3)