throw the baby out with the bath water字面意思是把婴儿和洗澡水一起倒掉，引申为将精华连同糟粕一起丢弃；不分好坏地全盘抛弃。

【例句】
When you attempt to design a new policy, don't throw the baby out with the bath water.
当你拟定新的政策时，不要把好的部份，连同不好的，一起扔掉。

You mustn't buy the cheap make-up, or you will throw the baby out with the bath water.
你一定不要买廉价的化妆品，否则的话你会得不偿失的。