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

1was having 2wanted 3saw.stopped.had 4had been walking walking. 5read 6didn't enjoy 7saw.had.didn't look 8had travelled 9had cleaned 10had finished 11was playing 12liked 13understood.had explaied 14what was he saying.... 15had been sitting 16opened.found.had already taken 17had already built 18was discussing 19arrived.were having 20saw.was trying