The visitors saw rows of houses the roofs are red.A. whereB. thatC. whatD. of which

问题补充：

The visitors saw rows of houses the roofs are red.

A. where

B. that

C. what

D. of which

答案：

A. where

B. that

C. what

(答案→)D. of which

解析：考查定语从句。本题定语从句的先行词是houses,定语从句中which指代先行词作为of的宾语，the roof of which=whose roof。句意：来访者看到了一排排的房子，这些房子的屋顶都是红色的。故D正确。