[藏污纳垢 / 藏污納垢, cáng wū nà gòuㄘㄤˊ ㄨ ㄋㄚˋ ㄍㄡˋ] to hide dirt, to conceal corruption (成语 saw); to shelter evil people and accept wrongdoing; aiding and abetting wicked deeds#65295
[吐故纳新 / 吐故納新, tǔ gù nà xīnㄊㄨˇ ㄍㄨˋ ㄋㄚˋ ㄒㄧㄣ] lit. to breathe out stale air and breathe in fresh (成语 saw, from Zhuangzi 庄子); fig. to get rid of the old and bring in the new, See Also: 成语, 庄子#75382