Нужно сделать 15, просто по 14-му

                                               and a Dog
Once upon a time there was a horse whose name was Reginald.Every morning he was delivering milk, he usually met his friend Blackie, who was a little black dog. 
 Reginald didn’t want to be a milkman’s horse.He wanted to be a racehorse and win the Derbi.  And Blackie, who had rather short legs, wanted to be able to run very fast, like a hound. 
 One afternoon they were sitting in Reginald’s stable.Suddenly Blackie said that he had, an idea.  
«Why do we not eat coal?» — he said. «Trains eat coal a run fast.»
  
They thought about this for a long time, and at last Reginald said: «Let’s try it,» 
 So they went down to the coal cellar. They were going to take some some coal, when Mrs Marry, the landlady, came in.
  «What! You are stealing my coal!» —  she began to cry, and she picked up a piece of coal and threw it at them.They ran away. They had never run so fast in their lives before.
 Just then the Mayor was looking out of the window.  
«Oh, that horse can run fast I’m sure it can win the Derby, look at the dog; it’s a real hound I’ll give them each a medal.» And he did. 

1. I can stay in bed tomorrow morning because I don't have to work.
2. Whatever you do, you mustn't touch that switch. It`s very dangerous.
3. You mustn't forget what I told you. It`s very important.
4. We don't have to leave yet. We`ve got plenty of time.
5. Ann was feeling ill last night. She had to leave the party early.
6. I had to go to the bank yesterday to get some money.
7. The windows are very dirty. I must clean them.
8. The windows aren`t dirty. You don't have to clean them.
9. We arrived home very late last night. We had to wait half an hour for a taxi.
10. These cakes are very nice. You must have one.
11. We don't have to take an umbrella. It`s not going to rain.