Переделать из действительного залога в страдательный залог. 1) the teacher explaing new material at every lesson. 2) the teacher is explaing new material now. 3) the teacher has been explaining new material for 10 minutes since 9 o'clock in the morning. 4) the teacher explained new material yesterday. 5) the teacher was explaining new material yesterday at 10 o'clock.

1) New material is explained at every lesson.
2)  New material is being explained now.
3)  New material has been being explained for 10 minutes since 9 o'clock in the morning. - Но это очень сильно притянуто за уши, так как даже не все лингвисты соглашаются, что такая форма (Present Perfect Continuous Passive) допустима. 
4) New material was explained yesterday.
5) New material was being explained yesterday at 10 o'clock.