Question

Euclid was an ancient Greek scholar who ...

wrote a geometry textbook that was used for nearly 2,000 years.
calculated the value of the infinite number known as pi.
computed the circumference of planet Earth.
developed military tactics that still apply today.

Answer 1

Euclid was an ancient Greek scholar who

A: wrote a geometry textbook that was used for nearly 2,000 years.

Answer 2

Euclid was an ancient Greek scholar who wrote a very influential textbook which had been used since he wrote it for a very long time; his geometry textbook had, according to some sources, been in use for almost 2000 years since he had written it. But this has been a debate among historians whether it was really that long.