Change the number of the italicized nouns and make all necessary changes:
1. The book is on the shelf.
2. This is an English dictionary.
3. The roof of the house was covered with snow.
4. This factory has a good laboratory.
5. A copy of the contract was sent to Lviv.
6. Where is the knife?
7. The child is playing in the yard.
8. The tomato is ripe.
9. The cat caught a mouse.
10.I have hurt my foot.
11. The story is very long.
12. He is a nice person.
13. The speech was very interesting.
14. He left the key on the table.
15. The last leaf fell from the tree.
16. I like his new play.