答案:Judging by what they say and do.
Judging by what they say and do. 本题问“你需要怎样做才能判断双方是否速成一致”。根据问题中关键词“in agreement”可确定文中相关部分在第五段三行处。文中提到:“if one person makes a clear and definite offer and another person unconditionally accepts the offer, then it is reasonable to say that the two of them are in agreement. There is no attempt to look inside their minds to find out what they are really thinking: it is what they say and do that counts.”(如果一方做出明确的提议并且对方表示五条件地接受,那么可以说双方达成了一致。不必关心他们实际怎么想的,重要的是根据他们所说的话和所做的事就足以做出判断)。因此,本题答案为:Judging by whet they say and do。