Qual é a diferença entre it e that ?Podes indicar apenas respostas exemplo.

"It" is used to replace nouns so that you're not repeating it a lot of time. E.g. Instead of saying "I finished my homework. Could you have a look at my homework?" you should say "I finished my homework. Could you have a look at it?"

("It" is also used when something isn't male or female, or when you don't know if something is male or female. So, you can use it to call inanimate things and animals. E.g. If my cat was playing, I can say, "Look! It's playing!")

"That" is used to refer to things that are away from you. E.g. If you had a book in your hand, I could say, "Can I see that book in your hand?"
If I'm talking about your question, I might say, "That is an interesting question".

If someone else said, "That's an interesting question", I can agree by saying, "Yes, it is". Here the "it" is replacing the adjective/noun phrase. I know, in some cases it's a bit confusing, but I'm sure you'll get it with more exposure to English :)