Exercise 21. Use doesn't, don't, aren't, isn't or am not.

The book isn't on the table.
Those students don't study very hard.
The men aren't from South America.
I am not ready yet.
That woman doesn't come from Europe.
The children aren't in the room.
Those people don't like coffee.
Miss Smith isn't a student here.
Mr. and Mrs. Brown don't study English. 
The money isn't on the table now.
That student doesn't know the answer.
You aren't from England.
We don't know that word.
Mr. Brown isn't busy today.