Great-grandparents

We are living on average today thirty four years longer than our great-grandparents did.

Source: tatoeba (1689063)

Only two of my great-grandparents lived long enough for me to meet them.

Source: tatoeba (4286972)

All their great-grandparents were dead before Tom and Mary were born.

Source: tatoeba (4286978)

Many people don't know the names of all their great-grandparents.

Source: tatoeba (7502074)