a glass shelf
玻璃架子
on the top/bottom shelf
在顶层/底层架子上
One wall had shelves from floor to ceiling, crammed with books.
一面墙是高及天花板的书架,上面塞满了书。
It's often cheaper if you buy wallpaper off the shelf, rather than having to order it.
如果你买现成的墙纸,通常会比订购的要便宜。
off-the-shelf goods/clothes
现成的货物/衣服