THERE IS A... THERE ARE SOME...

PRESENT (+):
There is a new neighbour in that flat.
There are new neighbours in our block of flats.

PAST (+):

Last month, there was an Italian person on the third floor.

Last week, there were some English persons on the first floor.

PRESENT (-):
There isn't any TV set in the kitchen.
There aren't many cupboards in the kitchen.

PAST (-):

Two months ago, there wasn't a computer in his bedroom.

Three weeks ago, there weren't any pictures on the walls.

PRESENT (?):
Is there a bath in the bathroom?  Yes, there is.  / No, there isn't.
Are there any chairs in the garden?  Yes, there are.  / No, there aren't.

PAST (?): 

Was there any piece of furniture in the dining room?  Yes, there was.  / No, there wasn't.

Were there any people in the house?  Yes, there were. / No, there weren't.