his book was much better than those written so far on this city 为什么要用written

his book was much better than those written so far on this city 为什么要用written

than those written =than those which were written
两种理解,第一种：
可以还原成定语从句,然后省略主语谓语部分
第二种理解,those(books)和write 是动宾关系,所以用过去分词

those 指的是 books(其他的书)，这些书是被写出来，所以是被动，就用written(在这里是形容books)

written so far on this city 是过去分词短语作定语=that

written 意思是过去已经写过的那些书。

因为书是被人写，所以是被动关系，被动是用动词过去分词
P.S.主动关系则是动词ING形式