ex2

1. are, in, 2. in, there's 3.on, in 4. is, in 5. there's, on 6.are, on.

ex3

1.there is 2.there is 3.there are 4.there are 5.there is 6.there is 7.there are

ex4

1.on 2.there are 3.in 4.on 5.there is 6.on 7.there are 8.on 9.on 10.in