Choose the correct form of the italicized words below, and give the reason for your choice.
1. If it don't—doesn't fit you, we shall alter it.
2. I knew—knowed I was right.
3. Aren't—ain't you glad we came?
4. Ain't—isn't he well?
5. We done—did the right thing.
6. Let—leave the book on the table.
7. Let—leave me do as I planned.
8. Mary has broke—broken her arm.
9. My mother has gone—went to Boston.