1.
1) He had remembered that he didn`t lock the door.
2)I had said he wrote the exercise last Monday.
3)The father had wanted who broke his favourite car.
4)The students had known that we bought radio-set.
5) I had come late at school because I missed the train.
6) When arrived at the party Tom had already gone home.
7) Her uncle had said he losed the key.
2.
Честно сказать, я считаю неправильным это упражнение, приведу пример моего несогласия:
1)Моя сестра радовалась, потому что .. Чтобы во второй части было время Past Perfect , то нужно, чтобы было действие, которое совершается после первой части(по времени), но что можно придумать, ведь у нее есть причина радоваться, и ее во второй части нужно указать, но временем Past Perfect это невозможно! Пусть смотрят эксперты, может, я не права.
3.
1) The cat ate all sausages before we had become home.
2) Mary had come when I read the book.
3) I had gone out gor a walk after I did my homework.
4) I had arrived at the party when my brother went home.