5. Because he didn't do his homework, the teacher told him he would ______ after school.

Решение:

В данном контексте, если ученик не сделал домашнее задание, учитель, вероятно, назначит ему наказание или дополнительное занятие. Подходящим вариантом может быть 'stay' (остаться) или 'detention' (оставление после уроков).

5. Because he didn't do his homework, the teacher told him he would stay after school.