The flower in the vase is expensive.

it is expensive,the flower in the vase.不然只能这样分成两句说.或者改成主语从句,what is expensive is the flower in the vase.
楼主是要强调因为在花瓶里所以贵吗?The flower is expensive in the vase.这里改变了语序但是语义没有变,也还是一样的句子结构,主语+谓语+表语.in the vase相当于一个副词修饰主语.这样改没有问题,但是一般为了通顺会把in the vase 放在flower 后面.这个和原句本质上相同,如果要强调花瓶,可以说,the flower is expensive because it is in the vase.(逻辑上有点奇怪）,或者,the flower is expensive,so I put it in the vase.(so it is put in the vase.)