wǒ / zài / jiù shū diàn / táo dào / yī běn / jǐ hé yuán běn / nèi róng / shí fēn / zhēn guì我在旧书店淘到一本几何原本,内容十分珍贵。I found a copy of Euclid's "Elements" at a second-hand bookstore, and its content is very precious.