Talking about where something is from.
Talking about what something is going to or for.
Talking about where something is located.
Talking about something happening now.
Talking about something that happened a while ago.
Talking about how to give orders.
Talking about how one thing is another thing.
Talking about who is doing what in a sentence.
Talking about something happening right now, continuously.
Talking about something that might, could or will happen.
Talking about something that isn't, won't or didn't happen.
Talking about using some object to do something.