Question

Ответьте, используя Past Perfect Continuous. HOW LOHG HAD 1)...the students been listening attentively to the dialogue before they could understand the basic meaning? (for an hour) 2)... the children been walking before the granny called them? (for 2 hours)

Answer 1

the students had been listening to music for an hour before they could understand the basic meaning.
The children had been walking for 2 hours before granny called them.