这个结构用来表示虽然不必要但却已完成的动作：
I neednt have written to him because he phoned me shortly afterwards.
我本来不需要给他写信，因为不久之后他就给我打了电话。(但我的确写了，因而浪费了时间。)
You neednt have brought your umbrella for we are going by car.
你本来不用带雨伞，因为我们将要坐车去。(但是你却多余地带了伞。)
He neednt have left home at 6:00;the train doesnt start till 7:30.
他本不必6点就离开家;火车7点30分才出发。(因此他要等一个小时。)
To be on the same wavelength 意气相投
Accountability, liability and responsibility 的区别
Knock your socks off 叹为观止
Pay through the nose for something 出高价，花大价钱
Butterfly numbers drop a mystery, say experts 英国蝴蝶数量下降现象令专家费解
So far 的用法
Turn a blind eye 视而不见
Dictionary and other words 与“词典”相关的近义词
To have deep pockets 资金雄厚
Have your feet on the ground 脚踏实地