Я сразу буду писать исправленный вариант

1)The parents wanted to know if religious education had been compulsory at that school.

2)Some students couldn't remember what home task they had yesterday.

3) had given

4)had been

5) ничего

6) if her mother liked going

7) if the students had already read

8)what mark her son had got

9) if he had been ready

10)he would

А на шестом можно долго гадать, но, скорее всего, туда нужно вставить твои новые слова из этого юнита, проверь.