1. be disappointed 后接介词，情况比较，大致区别如下：
(1) 表示对某人感到失望，通常用介词 with, in。如：
I’m disappointed in you! How could you have lied like that? 你让我失望了，你怎么能像那样说谎呢?
My parents will be disappointed in [with] me if I fail in the exam. 要是我考试不及格，我父母会对我感到失望的。
(2) 表示对某一行为(doing sth)感到失望，通常用介词 at, about等。如：
We are all disappointed at [about] his failure. 我们都为他的失败而感到失望。zn
He was really disappointed about [at] not being able togo. 他未能去成实在感到失望。
(3) 表示对某一事实或情况感到失望，一般用介词 with, at, in 等。如：
He’s disappointed at [in] the result. 他对结果感到失望
He must be very disappointed with [at, about] your examresults. 他对你的考试成绩一定非常失望。
(4) 表示因得不到某东西或实现不了某愿望而失望，通常用介词of。如：
I was disappointed of the car. 没等到车子我感到很失望。
He was disappointed of his ambition. 他因实现不了抱负而沮丧。