We are doing        experiment.
A.a          B.an            C.the

The bird can't                   .
A.fly         B.sing         C.swim

                ?I see a river.
A.What do you see?   
B.What are you doing?
C.What do you do?

    are the girls? They're in the woods.
A.Which  B.What  C.Where

       a big tree.
A.What      B.What a    C.How a