低级英语语法问题The ones on the shelf It is on the left 为什么第一句不加be动词

The ones on the shelf. The ones on the shelf.中为什么没有动词?one为什么能加s? put it on the left of the shelf.为什么用on 英语语法疑惑The book on the shelf is not mine.It's somebody elses' the ones(books) on the top shelf动词在哪里?句子结构? The ones onthe shelf可否说成The on the shelf one? the english book is on the shelf on/is/the/it/left排序 on the shelf还是in the shelf? the book on the shelf is mine.＿ ＿is＿?on the shelf划线 someone must have taken my watch,i left it here on the shelf what are on the shelf?what is on the shelf?为什么are不行?若有前后文,语法