1 had forgotten 2 had gone 3 had just had 4 had 4 had left 5 hadn't phoned 6 had come 7 hadn't met 8 had often heard of but had never seen 9 had given up ... had made 10 had already bought 11 had arraned 12 had sold 13 had finished
Здесь везде перфектная форма глагола в прошедшем времени и она состоит из глагола had и третьей формы главного глагола и показывает, что это действие произошло раньше другого и тоже в прошедшем времени.