①she must be fifty（对划线部分提问）划线的是fifty②she must be reading（变否定句）③I think the woman can be the youngest of us.（变否定句）
问题描述：
①she must be fifty（对划线部分提问）划线的是fifty
②she must be reading（变否定句）
③I think the woman can be the youngest of us.（变否定句）
答