unroofed

1·In 7th century BC, Romans inherited the traditions of Greece and built racetracks and unroofed amphitheaters.

公元前七世纪时罗马人继承希腊传统，就修建了赛马场和露天竞技场。

2·Annie: in the 7th century BC, Romans inherited the traditions of Greece and built racetracks and unroofed amphitheaters.

安妮：公元前七世纪时罗马人继承希腊传统，就修建了赛马场和露天竞技场。