为…所…: formal written passive
特殊句型 / special sentence patterns
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Subject (patient) + 为 + agent + 所 + V
为…所… is a passive of classical origin, very common in writing (history, press, literature). It equals 被…: 为人所知 = 被人知道 (known to people).
为 is read wéi here. The verb follows 所 directly, usually mono- or disyllabic, typically without 了 or complements. Set phrases to know: 为人所知、为…所用、为…所感动、不为所动 (remain unmoved).
Examples
这段历史很少为人所知。
Zhè duàn lìshǐ hěn shǎo wéi rén suǒ zhī.This period of history is little known.
他的作品深深地为读者所喜爱。
Tā de zuòpǐn shēnshēn de wéi dúzhě suǒ xǐài.His works are deeply loved by readers.
大家都被他的故事感动了，只有她不为所动。
Dàjiā dōu bèi tā de gùshi gǎndòng le, zhǐyǒu tā bù wéi suǒ dòng.Everyone was moved by his story; only she remained unmoved.
Common mistakes
✗ 为人所知道了 → ✓ 为人所知 (short verb, no 了).
✗ Reading 为 as *wèi*: ✓ *wéi*.
✗ 为…所 in everyday speech sounds bookish → ✓ 被.