The workers demanded that their employer their working conditions.
A. had improved
B. would improve
C. improve
D. will improve
网友回答
A. had improved
B. would improve
(答案→)C. improve
D. will improve
解析：考查虚拟语气：句意：工人们要求他们的老板改善工作条件。主句的谓语是demand，谓语动词用虚拟语气，用should do，should可以省略，选C。