Qual é a diferença entre " speak " " tell " e " talk " " say " ?Você pode indicar exemplo de resposta.

OK, these are a little tricky:

SAY
used for reported speech (when you are repeating what you said to someone); never has a person as a direct object

I said that I would be late.
What did he say?
She said that would be OK.
Don't say that to me! [Don’t speak those words to me!]

TELL
used for when you give information or instructions; almost always has an object (a person is the object) (because who you tell is more important than what you tell)

He told me that he doesn’t speak English. (If you said “He said to me that he doesn’t speak English” you would be reporting what he said but, usually, you are talking about the fact that he informed you that he does not speak English.)
Don’t tell me that! [Don't inform me of that! Don’t instruct me to do that.]
Did he tell you? He told me. [NOTE: *who* but not *what*]

TALK/SPEAK are very similar to each other

TALK
more informal, refers to conversational exchange

We stopped talking when he walked in.
Did he talk to you about the trip?

SPEAK
a little more formal; refers to one-way communication

Let me speak and then you can respond.
After hearing him speak, we all applauded.

You “speak” languages (English, Korean, etc.) only.
Can you speak French? No, I can speak Swahili.