Change into passive voice :
1. Does Mary cook good food?
2. Sonia is knitting a beautiful sweater.

Solution:

1. Does Marry cook good food? (Active Voice)
     Is good food cooked by Marry? (Passive Voice)

2. Sonia is knitting a beautiful sweater. (Active Voice)
   A beautiful sweater is being knitted by Sonia. (Passive Voice)