There is/are, There was/were

Present Form

It is used to say that something exists.
“There is” is for singular:
There is a chair in the living room.
There isn't a bathroom in the shopping centre.
Is there a computer in that classroom? Yes, there is / No, there isn’t.
“There are” is for plural:
There are chairs.
There are good teachers in that school.
There aren't apples in the fridge.
Are there books on the desk? Yes, there are / No, there aren’t.
* There is & there are = "hay" in Spanish.

Past Form

It is used to say that something existed or took place.
“There was” is for singular:
There was a chair in the living room.
There wasn't a bathroom in the shopping centre.
Was there a computer in that classroom? Yes, there was / No, there wasn’t.
“There were” is for plural:
There were chairs.
There were good teachers in that school.
There weren't apples in the fridge.
Were there books on the desk? Yes, there were / No, there weren’t.
* There was & there were = "hubo" / "había" in Spanish.