I once lived in a house roof has fallen in.A. whichB. thatC. whatD. whose

问题补充：

I once lived in a house roof has fallen in.

A. which

B. that

C. what

D. whose

答案：

A. which

B. that

C. what

(答案→)D. whose

解析：此题考查定语从句，先行词a house房子和下文主语roof是所有关系，引导词在从句中作定语，故用whose。选D。