Exercise on articles

Exercise on articles. Choose the right artilces a, an or zero article. In the sentences where it is not necessary to use a or an choose x.
1. A good friend usually gives good advice.
2. A child should drink milk at least twice day.
3. Please give me information where I can buy fruit.
4. A cow gives milk.
5. Tea is drink.
6. I can read book or magazine.
7. An apple grows on tree.
8. We can write letter on paper.
9. Gold is metal.
10. A table is made of wood.