也 (also) and 都 (all): always before the verb
【一10】【一13】【一39】范围副词“都”、关联副词“也”、并列复句
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
也 (yě, “also”) and 都 (dōu, “all, both”) are adverbs: they go after the subject and before the verb, never at the start or end.
我也是学生 (I'm a student too). 我们都是学生 (we're all students).
Combined, the order is 也 + 都: 他们也都是学生.
都 “looks left”: it sums up what comes before it: 爸爸跟妈妈都不在家 (neither Dad nor Mom is home).
都不 = “none”; 不都 = “not all”. 我们都不去 (none of us is going) ≠ 我们不都去 (not all of us are going).
也 also links two clauses: 这个房间很大，也很干净 (big, and clean too).
Examples
他是学生，我也是学生。
Tā shì xuésheng, wǒ yě shì xuésheng.He's a student, and so am I.
同学们都很认真。
Tóngxuémen dōu hěn rènzhēn.The students are all very diligent.
我和弟弟都学习中文。
Wǒ hé dìdi dōu xuéxí Zhōngwén.My younger brother and I both study Chinese.
我喜欢唱歌，弟弟也喜欢唱歌。
Wǒ xǐhuan chàng gē, dìdi yě xǐhuan chàng gē.I like singing, and so does my younger brother.
那些东西都很贵。
Nàxiē dōngxi dōu hěn guì.Those things are all expensive.
Common mistakes
✗ 也我是学生 / 我是学生也 → ✓ 我也是学生.
✗ 我们是都学生 → ✓ 我们都是学生.
✗ 都我们去 → ✓ 我们都去 (都 after what it sums up).