老生常談（老生常談）　

◎ 老生常談 lǎoshēng-chángtán

[be trite and commonplace;common talk of an old scholar;commonplace;platitude; standing dish; sunday schools truth; twice-told tale] 原義為年老書生的平凡議論,泛指經(jīng)常說起的老話

鄧颺怒曰:“此老生之常談耳!” 輅曰:“老生者見不生,常談者見不談。”——《三國演義》