问题补充：
There are lots of restaurants in our town. And most of are clean and cheap.
A. it
B. they
C. us
D. them
答案：
A. it
B. they
C. us
(答案→)D. them
解析：it人称代词,指代前文提到的单数事物;they人称代词主格,他们;us人称代词宾格,我们;them人称代词宾格,他们.句意：在我们镇上有许多饭店。他们中大部分又干净又便宜。结合语境可知下文人称代词指代的是前文的许多饭店，故用复数形式，做介词of的宾语，故用宾格形式。选D。
