Our country _______ a lot in the last fifty years. 

—Jim, could you tell me if you _____________ our party tomorrow?—I think I will if I _____________ free. 

 -All of us _______ sometimes. -You had better have a good rest when you are free. 

— You speak French so well. How long have you learned it? — ________ I was fifteen.

－Why does the river smell terrible? －Because the water_______.