Question

The teacher said that they ______ hard-working students.

A．is

B．are

C．were

D．was

Answer 1

C

考查宾语从句的时态。宾语从句的时态必须与主句保持一致。主句用的said，是过去式，故从句也用过去式，排除A、B；从句主语they是复数，故谓语也用复数，排除D。
句意“老师说他们是很刻苦的学生。”故选C。