Any suggested reviewer for IELTS exam?

The It's vs. Its page
If you're confused by these two little words, you've come to the right place.
It's is a contraction for it is or it has.

Its is a possessive pronoun meaning, more or less, of it or belonging to it.

And there is absolutely, positively, no such word as its'.

A simple test
If you can replace it[']s in your sentence with it is or it has, then your word is it's; otherwise, your word is its.

Another test
Its is the neuter version of his and her. Try plugging her into your sentence where you think its belongs. (It's better to use her for reasons I may explain someday.) If the sentence still works grammatically (if not logically) then your word is indeed its.

Examples
It's been good to know you. Contraction: it has
It's a bird! It's a plane! Contraction: it is

The dodo bird is known for its inability to fly. Possessive pronoun: its inability = the dodo bird's inability

From:
http://www.stormloader.com/garyes/its/#top

You means "www.selfaccess.com". That's really a great site for English learners especially for those who are preparing the international exams.
Hello from Vietnam = "Xin chao tu Vietnam"

Thank you
I like this site too - i think the essays and listenings are very helpful