use enwiki_p;

select REPLACE(l.ll_title, '_', ' ')

from langlinks l

join page p on p.page_id=l.ll_from

where p.page_namespace=14 and p.page_title in (select pla.page_title

                from categorylinks cla

                join page pla on cla.cl_from=pla.page_id

                where pla.page_namespace=15 and cla.cl_type="page" and

                                              cla.cl_to="WikiProject_Politics_articles")

and l.ll_from in (select m.ll_from from langlinks m where m.ll_lang="zh")

and l.ll_lang="zh"

group by l.ll_from