Помогите пожалуйста с домашкой по английскому(9 класс).
Очень благодарен заранее.

1was having2wanted3saw.stopped.had4had been walking walking.5read6didn't enjoy7saw.had.didn't look8had travelled9had cleaned10had finished11was playing12liked13understood.had explaied14what was he saying....15had been sitting16opened.found.had already taken17had already built18was discussing19arrived.were having20saw.was trying