when somebody say 以茶代酒 on the table , and that means he or she doesn't wanna drink wine to express his/her happiness ,maybe he is allergic to the wine ,or maybe he thinks that wine will be detrimental to his health or even maybe after the dinner he needs to drive ,so he cannot drink the wine ,but he also doesn't ruin all the fun ,so he choose the tea to replace the wine to express his emotion,you know ,when we wanna express some kind of emotion ,we often choose the wine