He paid the boy 10 yuan foe washing ten windows most of hadn’t been cleaned for at least

问题补充：

He paid the boy 10 yuan foe washing ten windows, most of hadn’t been cleaned for at least a year.

A. these

B. those

C. that

D. which

答案：

A. these

B. those

C. that

(答案→)D. which

解析：非限制性的定语从句，which 做of的宾语。