Question

He paid the boy ＄10 for washing ten windows, most of ________ hadn't been cleaned for at least a year．

1. A.
   these
2. B.
   those
3. C.
   that
4. D.
   which

Answer 1

D
这是一个定语从句。定语从句的先行词为windows。有的考生误认为前文提到windows，应用those代替而选B。但those不可用作关系代词引导定语从句。由于横线处前有介词of所以不能选that。