Past Perfect and Past Perfect Continuous Записать в Отрицательной и вопросительной форме
Предложение: The Smiths had been building their house for four years.

past perfect:

The Smiths hadn't built their house four years.

Had the Smiths built their house four years?

past perfect continuous:

The Smiths hadn't been building their house four years.

Had the Smiths been building their house four years?