Use of it and this

What is the difference between the use of IT and THIS?

This a big topic. Start with the references below.

http://dictionary.reference.com/browse/it

canadian45 What is the difference between the use of IT and THIS?This a big topic. Start with the references below. One difference in their use is that 'this' can be immediately followed by a noun; 'it' cannot be immediately followed by a noun. Write some sentences that give you trouble deciding whether to us 'it' and 'this'. Then we can explain which word you should use.

THIS points to something, or, more accurately, you point to something or show something when you use THIS.
IT refers to something that has been previously mentioned.

If I show you a book, I can say, "This is a book". I hold it so that you can see it.
If we have been talking about a certain book, I can say "it" instead of saying "the book" all the time. I can say, "It's a

This is to certify is commonly used. If it is put in place of this, would it be grammatically wrong? If it would be, why?r

It is a dog.
This is a dog.

It was my old camera

AnonymousIt is a dog.This is a dog.

this is a dog or it is a dog

it is to certify is wrong because what is being stated is just at hand, and for a close proximity this is the correct pronoun.
arvind shah

It was quite a surprise or this was quite a surprise

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