The town is no longer _____it was five years ago,______it was quite dirty.

这个小城镇不再是五年前那个很脏的小城镇了。

选C。

第一个空缺先行词，因为no longer不能做先行词，所以填the one that. 这个可以等于what。

第二个空定五年前这个时间，所以填when.

C
what it was five years ago
what it was 表示(城镇的)状态,
when it was quite dirty是非限制性定语从句,修饰" five years ago".

C
what先作is的表语，再做was的表语，只有what可以一词两用
后边从句已经有主语it，所以只能填when

C what ; when

c

c