Each sentence below contains a mistake. Write the mistake and correct it.
1. This cooker, which my sister bought it yesterday, is very expensive.
2. I haven't finished to decorate the Christmas tree yet.
3. The gas from the chemical factory is extreme harmful to our healthy.
4. My son didn't worn that uniform since last year.
1. This cooker, which my sister bought it yesterday, is very expensive.
This cooker, which my sister bought it yesterday, was very expensive.
2. I haven't finished to decorate the Christmas tree yet.
I haven't finished decorate the Christmas tree yet.
3. The gas from the chemical factory is extreme harmful to our healthy.
The gas from the chemical factory are extreme harmful to our healthy.
4. My son didn't worn that uniform since last year.
My son hasn't worn that uniform since last year.
