------what made Mary so upset?为何不能用Her bike being lost 回答?
问题描述：
------what made Mary so upset?为何不能用Her bike being lost 回答?
答
因为her bike being lost是一个原因状语结构，不能作为主语或是宾语
答
因为her bike being lost是一个原因状语结构,不能作单句.要回答,应用：
She lost her bike.或者
Her bike was lost.