3. Our grandparents not be as familiar with technology in their childhood as we are now.

3. Our grandparents were not as familiar with technology in their childhood as we are now.

В данном предложении использована форма Past Simple глагола to be (was/were) в отрицательной форме, чтобы показать, что в прошлом наши бабушки и дедушки не были так знакомы с технологиями, как мы сейчас.

Ответ: Our grandparents were not as familiar with technology in their childhood as we are now.