Are "it" and "this" almost always interchangeable? When I talk to people, I often use "it" or "this" interchangeably, because I have no idea when exactly I can use "this". In a dialogue or conversation, is it true that they are interchangeable. If not, could you give some insightful examples?
"The bill will get passed if the Democrats rally behind the President."
"It won't, and you know it. The Democrats will never support a radical socialist and his crazy policies."
"This isn't a bill that you can't pass. If they don't pass it, then they would have achieved nothing in the last 2 years. They can't afford to block this if they want to remain in power."