Из active voice в passive voice 1)they discuss different problems at the lessons. 2)the builders built a new school. 3) pupils must take exams at the end of each stage of education 4) they will know the result of the tests in a few days.

1 Different problems are discussed at the lessons
2 A new school was built
3 Exams must be taken  at the end of each stage of education
4 The result of the test will be known in a few days