1.后接介词

2. be disappointed 后接不定式

3. be disappointed 后接that 从句

4.有时可单独用作状语。

be disappointed with sb.对某人失望

be disappointed about sth.对某事失望

后接介词时，情况比较复杂，大致原则如下：

(1)表示对某人感到失望，通常用介词with, in。如：

He is very disappointed in his new secretary. 他对他的新秘书感到很失望。

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。

He was really disappointed about [at] not being able to go. 他未能去成实在感到失望。

(3)表示对某事感到失望，一般用介词about, at, with等。如：

I felt disappointed about the game. 我自己对这场球赛感到失望。

I was disappointed at [with, in] the result. 我对那结果感到失望。

(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。