英语语法分析

BHP Billiton Ltd. and Rio Tinto Group led mining shares lower.

必和必拓公司和力拓集团领跌矿业板块。

BHP Billiton, both of which have large operations in Australia.

这两家大供应商都在澳大利亚拥有大量业务。

BHP Billiton, Rio Tinto's larger rival, ended a six-year run of record profits.

必和必拓，力拓的最大竞争对手，结束了长达六年营运利润破纪录的状况。