–What made you so sad?-- my cellphone.A. LoseB. LosingC. To loseD. Lost

问题补充：

–What made you so sad?

-- my cellphone.

A. Lose

B. Losing

C. To lose

D. Lost

答案：

A. Lose

(答案→)B. Losing

C. To lose

D. Lost

解析：考查情景交际和非谓语动词。句意：--是什么让你这么伤心？--丢失了手机(让我很伤心)。答语使用的是动名词作主语，Losing my cellphone是主语部分，答语省略了made me sad。故选B。