the city has a current population of about 36000 which is expected to rise to about 129000 by 2012……这句话是什么结构?which后面的句子是

问题描述:

the city has a current population of about 36000 which is expected to rise to about 129000 by 2012……这句话是什么结构?which后面的句子是修饰什么的?

which是定于从句,修饰population,前面就是正常的主谓宾