she lives upstairs/ downstairs to my apartment. (单元房）I live in the buidling opposite (to) yours but upstairs I live on the 3rd floor of the buidling opposite yours. \此处upstairs, dowstairs 皆为副词
第一个不是因为要和前面的 主语对应 而是above后面要接的是宾语 而mine是表示所有格例句：she lend a book to me. 第二个 below 表示正下方 under 也可以 第三个 我就站在 / 坐在，你家楼下 I just stand/sit at your downstairs 第四个 我刚刚从你家楼下 / 你家门前 经过 I just from your home / house with you
