用法、訳について。
until he was 10years old, Einstein was not very good at talking. Even when he became an adult, he said,I rarely think in words at all.
He liked to go and sit by himself and think and dream.
Einstein really liked blocks, and he also liked to build houses from playing cards. They say that he could make a house that was 14 stories tall! He did not worry about how many times the houses fell down, and he
worked on them for hours and hours.
文の訳をお願いします。
また、
he worked on them for hours and hours.
の、them はどういう意味ですか?