to state the existence in the classroom

There is

There are

Are there

Is there

There is two chairs and desks in the classroom.

There are two chairs and desks in the classroom.

There are two chair and desk in the classroom.

There is a chair and desk in the classroom.

There is

There are

Is there

Are there

Whiteboard

Pictures

Desks

Air Conditioner

How many pens are there in the pencil case?

There are four pens in the pencil case.

There are no pens there.

Is there four pens in the pencil case?

There are

a

books

on the table

There are a clock on the wall.

There is one clock on the wall.

There is no clock on the wall.

There is clocks on the wall.

There is

Is there

There are

Are there