1) The essay WAS DISCUSSED yesterday.

2) They DISCUSSED the essay yesterday.

3) The essay WILL BE DISCUSSED tomorrow.

4) We WILL DISCUSS the essay tomorrow.

5) If we DISCUSS the essay tomorrow, you WILL WRITE another one.

6) The essay must BE DISCUSSED tomorrow.

7) The essay must HAVE BEEN DISCUSSED last week.

8) I hope the essay WILL BE DISCUSSED tomorrow.

9) They’ll write the test tomorrow. They ARE DISCUSSING the essay at the moment.

They HAVE BEEN DISCUSSING it since lunch.

10) We HAVEN'T DISCUSSED the essay yet.