Perhaps you should try some spelling variations:
wang yang » wang liang, wang yanling
than coal » than modal, than cost, when coal
zhong tai » hong tan, hong hai, zhong zhi
than oil » than only, than one, than our
liang li » ling li, qiang li, liang wei
qian yi » qian yan
yang » ryang
yan » ryan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: wang yang ((than oil) or (than coal)) coal ((liang li) or (qian yi)) ((zhong tai) or (wang yan)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wang yang ((than oil) OR (than coal)) coal ((liang li) OR (qian yi)) ((zhong tai) OR (wang yan)) ;.
• Adding a wildcard symbol may retrieve word variants: wang yang ((than oil) or (than coal)) coal ((liang li) or (qian yi)) ((zhong tai) or (wang yan)) ;*.