What is the difference between it and that as a demonstrative pronoun?

There is a difference! That generally refers to an object in a direction, meaning that (side), that, that, that situation.

That is my girlfriend.

I like that.

It does not have this specific restriction, when the contemporary word is used, the scope is larger than that, and all those that can use this and that can be used can be replaced by it, that is, that(this) belongs to it, and is a subset of it (element?). ）

that"with"it"are two pronouns, and both are used differently.

that"Refers to a noun or noun phrase mentioned earlier and is used to emphasize or point out the thing or situation being talked about. For example:

that book is really interesting.(That book is really interesting.) ）

i can't believe that you did that.(I can't believe you did that.) ）

it"It is used to represent an object or concept mentioned before the first hand, and can also be used to refer to the subject of the entire sentence. For example:

it is raining outside.(It's raining outside.) ）

i heard a loud noise, but it turned out to be just the wind. it scared me though.(I heard a loud bang, but then the stool was now just the wind.)

Still, it scared me. ）

it is that the emphatic usage is as follows:

When the subject, object, and adverbial in an emphasis, an emphatic sentence is commonly used: it is was+ the part that is emphasized

he bought three books in the bookstore yesterday.

Emphasis on the subject: it was he that who bought three books in the bookstore yesterday

Emphasis on the object: it was three books that he bought in the bookstore yesterday

Emphasis on adverbials: it was in the bookstore that he bought three books yesterday

It and that are both demonstrative pronouns, but the conditions under which they are used are very different, and all three words have some fixed usages, specifically the distinction is as follows:

1. When this or that is the interrogative sentence of the subject, it should be replaced by this or thatSuch as:

is this a book?Is this a parody of the book?

yes,it is.Yes, this is the book.

what’s that?What's that big dilemma?

it’s a kite.It was a kite.

2. Refers to a baby of unknown sex, an unidentified person, or a person who only hears his voice but does not see himSuch as:

it’s a nice picture. who’s in it?This is a good-looking **, who is the person on it?

me!It's me!

3. IT is often used in place of the things mentioned above. Such as:

the pen doesn’t work. it’s lily’s.The pen is broken, it's Lily's.