1. rita writes letter
   passive: the letter is writen by rita
2. she teaches the elementary students
   passive: the elementary students are taught by her
3.  Right now, Sarah is writing the letter.
passive: Right now, the letter is being written by Sarah.
4.Sam repaired the car.
passive: The car was repaired by Sam
5.The salesman was helping the customer when the thief came into the store.
passive: The customer was being helped by the salesman when the thief came into the store.
6.Sally is going to make a beautiful dinner tonight.
passive: A beautiful dinner is going to be made by Sally tonight.
7. Many tourists have visited that castle.
passive: castle. That castle has been visited by many tourists.
Chef Jones had been preparing the restaurant's fantastic dinners for two years before he moved to Paris.
passive: The restaurant's fantastic dinners had been being prepared by Chef Jones for two years before he moved to Paris.
9.At 8:00 PM tonight, John will be washing the dishes.
passive: At 8:00 PM tonight, the dishes will be being washed by John.
10. They will have completed the project before the deadline.
passive: The project will have been completed before the deadline.

semoga membantu :)