Encore et Aussi : 还, 也, 又, 再

也 (yě) : Also / Also. Always placed before the verb.
[cite_start]我也去。
Wǒ yě qù. (I also go).

还 (hái) : Still / Also / Moreover. Indicates continuity or adds information.
[cite_start]他还在睡觉。
Tā hái zài shuìjiào. (He is still sleeping).

再 (zài) : Again (future). For a repetition to come or be desired.
[cite_start]明天再说吧。
Míngtiān zài shuō ba. (We'll talk about it later).

又 (yòu) : Again (already realized). For a repetition already realized.
[cite_start]今天他又迟到了。
Jīntiān tā yòu chídào le. (He is still late today).

Key Nuance Point: 又 vs 再

昨天他又迟到了。
Zuótiān tā yòu chídào le. (He was late again yesterday).

明天别再迟到了。
Míngtiān bié zài chídào le. (Don't be late again tomorrow).