for the best: Having or producing a better result; in a way that will achieve the best result; Said of something that is a positive occurrence (especially when it initially seems bad or problematic). This is usually an expression of hope or insight after something has gone away. If you say that something is for the best, you mean it is the most desirable or helpful thing that could have happened or could be done, considering all the circumstances.
中文释义：for the best表示虽然现在不好，但“结局总会是好的”，也就是说考虑到所有的情况，它是可能发生或可能做的，最令人满意或最有帮助的事情。我们可以将This is probably for the best直接背下来， 安慰人时就可以用上这句话。
例句：Whatever the circumstances, parents are supposed to know what to do for the best. （不管在什么情况下，父母都应该知道怎么做才是最好的。）