《资治通鉴·唐纪·唐纪四十六》
过了几天，大家才知道田绪杀了他的堂兄，虽然为田绪杀了田悦而愤怒，为自己拥立田绪而懊悔，然而，田绪已经就任，也就对他无可奈何。
后数日，众乃知绪杀其兄，虽悔怒，而绪已立，无如之何。
A few days later, everyone found out that Tian Xu had killed his cousin, and although they were angry at Tian Xu for killing Tian Yue and regretted supporting Tian Xu, nevertheless, Tian Xu had already assumed office and there was nothing that they could do about it.
<s>[INST] Kindly elucidate the central themes in this passage in English: 后数日，众乃知绪杀其兄，虽悔怒，而绪已立，无如之何。 [/INST] A few days later, everyone found out that Tian Xu had killed his cousin, and although they were angry at Tian Xu for killing Tian Yue and regretted supporting Tian Xu, nevertheless, Tian Xu had already assumed office and there was nothing that they could do about it.</s>
Kindly elucidate the central themes in this passage in English: 后数日，众乃知绪杀其兄，虽悔怒，而绪已立，无如之何。
user
A few days later, everyone found out that Tian Xu had killed his cousin, and although they were angry at Tian Xu for killing Tian Yue and regretted supporting Tian Xu, nevertheless, Tian Xu had already assumed office and there was nothing that they could do about it.
assistant