I often get confused between 'This' and 'It' during sentence making, and because of that I face difficulties in sentence making. Few examples are given below-
It is the world's top choral events.
Have you seen it before?
It is enough.
It is impossible.
It is a boy
My confusion is here we can also use 'This' as well-
This is the world's top choral events.
Have you seen this before?
This is enough.
This is impossible.
This is a boy
Please give me some tips or tell me the proper use of 'this' and 'it'. Its very confusing.