How to say you should not laugh at his mistake. in Japanese
1)
あなたあなた(anata) (pn,adj-no) youはは(ha) (int) indicating a subject/yes/indeed/well/ha!/what?/huh?/sigh彼の彼の(kano) (adj-pn) that誤り誤り(ayamari) (n) error/mistake/slip/bugをを(wo) (prt) indicates direct object of action/indicates subject of causative expression/indicates an area traversed/indicates time over which action takes place/indicates point of departure or separation of action/indicates object of desire, like, hate,笑ってno dictionary result, likely a conjigated verbno dictionary result, likely a conjigated verbはは(ha) (int) indicating a subject/yes/indeed/well/ha!/what?/huh?/sighいけないいけない(ikenai) (exp) wrong/not good/of no use/hopeless/past hope/must not do。。(。) Japanese period "."
