When do I use "there"?
When directions or places are involved:
- "It's over there!"
- "Get out of there!"
- "There isn't any more soap!" (This one isn't quite so obvious with the 'place' thing)
- "How do we get there?"
- "What are you doing there?"
- "There's that escaped chinchilla that was on the news."
When do I use "their"?
When possession or ownership is involved:
- "That's their overripe watermelon."
- "Is this their address?"
- "This one is theirs, not ours."
When do I use "they're"?
I'm saving the easiest one for last: use "they're" only when "they are" would fit too*:
- "They're coming!" ("They are coming!")
- "You'll have to ask them when they're here." ("You'll have to ask them when they are here")
- "They're big, sweaty, ignorant and have hairy hands." (They are big, sweaty, ignorant and have hairy hands.)
* There's that apostrophe [this thing --> ' ] again, standing in for missing letters.