The word "they" refers to_______

A

- Hướng dẫn giải

Phương pháp giải:

Giải chi tiết:

A

They = reservoirs and canals

“The temples and palaces of Angkor were constructed around a series of artificial reservoirs and canals which were annually flooded to capacity by the Mekong River. Once filled, they were used to irrigate the surrounding paddies and farmland during the course of the year. “