The house walls are red is where my grandfather used to live ten years ago.A. whichB. of

问题补充：

The house, walls are red, is where my grandfather used to live ten years ago.

A. which

B. of which

C. whose

D. that

答案：

A. which

B. of which

(答案→)C. whose

D. that

解析：考查非限制性定语从句：句意：墙体是红色的房子是我祖父前住的地方。这是非限制性定语从句，先行词是the house，定语从句中的walls缺少定语用whose引导定语从句，名词+of which也可以引导定语从句，但是名词walls前面要加定冠词the，所以选C。