“What makes her so unhappy?” “____ one of her favorite books.”
A、Because she lost
B、Because of her losing
C、She lost
D、Her losing
【正确答案】：D
【题目解析】：由问句中的baiwhat作主语可知，要选择du的答案必须能作主语。在四个选项zhi中A和B只能做原因状语；而C不能dao直接作状语，可加上引导词that，即That she lost one of her ...makes her so unhappy.。答案选Her losing one of...makes her so unhappy，则可以，因为动名词可作主语。
