bookcase可以用in也可以用on，具体应该要联系语境，例如It is on the bookcase意为在书架上；It is in the bookcase意为在书柜里。介词in与on两者用法有一定的区别，In表示地点时，后面一般接大地点，如in London，in Beijing。in表示空间位置时，表示“在范围之内”。例如：The ball is in the box.球在盒子里。on表示地点的时候指与线或面接触，意为在什么上边；在什么旁边。例如：The photo was on the wall。Nanjing is on the ChangJiang River。

The bookcase is screwed to the wall.

书架用螺丝固定在墙上了。

The bookcase fits neatly into the alcove.

书架正好放得进壁凹。

Putting the bookcase together should be a simple assembly job.

组装书橱应该是个简单的装配活。

The microphone was cunningly concealed in the bookcase.

话筒被巧妙地隐藏在书柜里。

The study was lined from floor to ceiling on every wall with bookcases.

书房的四面墙都摆满了书架，从地板一直到天花板。

Gil rose and went to his bookcase and took down a volume.

吉尔站起身，走到书架跟前，取下一本书。

Mary left her most precious possession—a small bookcase—to her niece.

玛丽把她最珍视的财产——一个小书架，留给了她的侄女。

We went for the bottle of whiskey that we had stashed behind the bookcase

我们去拿那瓶藏在书架后面的威士忌。

Bookcases flank the bed

床的两侧有书柜。

This bookcase has five shelves.

这书架有五格。

Reading in a pedantic way may turn you into a bookworm or a bookcase,and has long been opposed.

读死书会变成书呆子，甚至于成为书橱，早有人反对过了。

What materials do you need to make a bookcase?

做个书架需要些什么材料？

He gave them lovely bookcase in gratitude for their kindness.

他送给他们一个漂亮的书柜以感谢他们的好意。

This bookcase is too unstable to hold so many books.

这书橱很不结实，装不了这么多书。

A lot of ligneous door,bookcase in my home,ambry is to have breath,have life.

我家里的很多木制的门、书柜、橱柜都是有呼吸、有生命的。

Do you want to design your own taste of bookcase?

你想要设计拥有自己品位的书橱吗？

I want the bookcase to stand free of the wall.

我想让这个书橱不要靠着墙。

I love this bookcase,because I love read books.

我喜欢这个书柜，因为我爱读书。

There are many good books in his bookcase.

他的书架里有很多好书。

I would say the bookcase contains about 100 books.

我估计这个书橱装有上千册书。

Creative bookcase inspired by the pieces from the famous puzzle game.

受该著名拼图游戏当中的方块所启发的创意书架。

The dutch designers at atelier 010 have created the bookworm bookcase.

atelier010的荷兰设计师设计的蛀书虫书架。

Next month ikea will introduce a new,deeper version of its ubiquitous"billy"bookcase.

下个月宜家家居将推出其畅销品牌“毕利”书柜的一款全新改良版。

Also for gaining space the room has a fix desk with a sliding element for your computer,put in front of a bookcase.

同样是为了争取空间，房间内还有一张固定在书架前的桌子，桌子带有一个放电脑的可滑动构件。

I went to a small room next to the drawing-room.Taking a book from a bookcase,I climbed up into the window-seat.

我溜进了会客室隔壁的一间小屋子，从书架上拿下一本书，爬上了窗座。