We can add the suffixes - er, - or, - ist to verbs or nouns that describe people. We usually add - er and - or to verbs and - ist to nouns. Write the nouns for these words. Use your dictionary if necessary.
1. art - artist
2. sing
3. drive
4. invent
5. science
6. economy
7. teach
8. play
9. photograph
10. direct
11. write
12. build