Billy _____ to hand in his homework,but he had left it at home.(选下列答案.说明理由!）

题目

Billy _____ to hand in his homework,but he had left it at home.(选下列答案.说明理由!）
A.was telling B.told C.was told D.had told

答案

C,从后一句话可以看出,前一句话必须是过去式,因为后一句话是过去完成时,而此处应为被动语态因为Billy 是被要求去交作业,所以是was told