一道高中英语试题

Question

A high public tolerance for --- and low public awareness of --- noise pollution has provided bus video advertisers with a paradise ______ their businesses.
A. in which to expand B. which to expand in
C. where to expand D. that they expand in
答案是A。为什么？C不可以吗？

Answer 1

如果先行词(指定语从句修饰的那个表地点的词)前已有前置词(介词)，关系副词就用where ；如果先行词前没有前置词，此时既可以用where，也可以用in which,但在美国的TOEFL考试中一般要用in which。例如：①The offices,laboratory,and museum are situated at te top of the hill whe re they command a fine view.(参考译文：办公室、实验室和博物馆都坐落在山顶上，从那儿他们可以俯瞰周围秀丽的景色。)句中用where是因为top前已有前置词at。②The farmer uses wood to build a house in which to store grains.(译文：农民用木头造了一间房子，用来储存粮食。)

Answer 2

in which用于比较正式的场合，where用于较为口语的场合

参考资料：http://grammar.quickanddirtytips.com/where-versus-in-whichadverbs.aspx

Answer 3

选A，是因为定语从句。C，不能选的原因是paradise前是with，而不是in。追问

是定语从句没错，可在定语从句中where可以与in which 替换啊。
这里不是expand their businesses in the paradise吗？paradise是先行词，所以A是对的，那照此看，C应当也可以啊。
不明白啊~~呜呜