孤掌难鸣 (孤掌難鳴) gū zhǎng nán míng

gū zhǎng nán míng set phrase it is difficult for one person applauding alone to make much sound
Domain: Idiom 成语
Notes: By extension, it is dificult to achieve something without support (CC-CEDICT '孤掌難鳴'; Guoyu '孤掌難鳴')