In or at

[MsNyree]

When I’m telling someone that I’m disappointed about his or her behavior, how would I say it? I’m disappointed at your behavior or in your behavior. I’m disappointed at him or in him.

 

[albertino]

When I’m telling someone that I’m disappointed at/with/about his or her behavior, how would I say it? I’m disappointed at/with/about your behavior or in your behavior. I’m disappointed in him .

Be disappointed at/with/about something, but disappointed in somebody.

Hope that helps. Not a teacher~~;-)

 

[MsNyree]

Instead of saying, “I’m surprise at you!” say, “I’m surprise in you.”

 

[Deepurple]

Instead of saying, “I’m surprise at you!” say, “I’m surprise in you.”

Not at all. You see different adjectives may go with different prepositions.
We can say "I'm surprised at/by the news.” But there is no such thing as “I’m surprised at you!” or “I’m surprised in you.”

(Not a teacher)

 

[MsNyree]

How would I be able to tell what adjectives go with prepositions?

One person had written be disappointed at/with/about something

Be disappointed in somebody

 

[Deepurple]

How would I be able to tell what adjectives go with prepositions?

One person had written be disappointed at/with/about something

Be disappointed in somebody

Buy a book on learning prepositions or type "learning prepositions" in google search box for free.;-)