定义：

　　the last in a series of difficulties after which the situation is unbearable

　　一连串困难之后，可忍耐的极限

　　例句：

　　John has always been a trouble maker at school but when he set fire to someone's locker, it was the last straw and he was expelled.

　　约翰在旱校总是制造麻烦，当他对某人的橱柜放火时，实在让人忍无可忍，所以他被开除了。