皆 / 均 / 亦: all / equally / also (written)
副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
S + 皆/均 + V (= 都) | S + 亦 + V (= 也)
Monosyllabic adverbs of classical origin, very frequent in formal texts, 成语 and signs:
• 皆 = 都 ("all"): 人人皆知 (everyone knows), 皆大欢喜.
• 均 = 都 with a sense of uniformity: 各项指标均达到标准 (all indicators meet the standard).
• 亦 = 也 ("also"): 亦是如此 (the same holds).
They sit where their modern equivalents do: after the subject, before the verb.
Examples
这位诗人的名字，在中国可谓人人皆知。
Zhè wèi shīrén de míngzi, zài Zhōngguó kěwèi rénrén jiē zhī.This poet's name is known to everyone in China.
展出的作品均来自民间艺术家。
Zhǎnchū de zuòpǐn jūn láizì mínjiān yìshùjiā.All the works on display come from folk artists.
音乐如此，绘画亦是如此。
Yīnyuè rúcǐ, huìhuà yì shì rúcǐ.So it is with music, and so it is with painting too.
Common mistakes
✗ 皆 / 亦 in casual speech: ✗ 我们皆去吃饭吧 → ✓ 我们都去吃饭吧.
✗ 均 alone for "average": ✓ 平均.