Wah How to use "There is / isn't / are /aren't"

We use there + be to say that something exists, usually when we talk about something at the first time.

• In this room there is a table. (This room has a table.)
• There isn't a bed. (This place doesn't have a bed.)
• There isn't a cup of chocolate milk.

• There are many students in this English class.
• There aren't any seats left. 
• There aren't any available cars for the rental.

You can also use there with another auxiliary verb for example :

• There used to be a library here but now there is a hospital instead.
• There must be an angel playing with my heart. from There Must Be An Angel (Playing With My Heart) - Eurythmics