Verified answer

1 came , had cooked  2 returned, had done  3 entered, had opened 4 gave, had bought  5 showed, had drawn  6 gave, had brought  7 saw, hadn't washed 8 understood,  hadn't done  9 knew, hadn't come  10 returned  11 had returned 12 finished 13 had finished  14 thought,  had lost  15 told, had seen 16 woke up, had gone  17 thought,  hadn't come  18 told, had cooked 19 found,  had lost  20 came, had left