帮忙做一道关于英语现在分词用法的题

问题描述:

帮忙做一道关于英语现在分词用法的题
“What makes her so unhappy?”
“Her losing one of her favorite books.”
请这里的“丢”为什么用“Her losing”而不是用“because she lost”?

回答是正确的.Her losing one of her favorite books可以当名词用.作主语,回答是一个省略句.完整句子为Her losing one of her favorite books makes her so unhappy.
because she lost是做原因状语的,不能作主语