- 三天两头 sāntiānliǎngtóu frequentlypractically every day; happening very often or repeatedly
- 三天不打，上房揭瓦 sāntiānbùdǎshàngfángjiēwǎ spare the rod, spoil the child(idiom) Three days without a beating and a child will climb onto the roof to rip off the tiles; describes a child who becomes unruly or mischievous if not disciplined regularly.
- 三十三天 sānshísāntiān thirty-three daysA period of thirty-three days
- 三天两头儿 sāntiānliǎngtóur frequentlyalmost every day; very often; all the time
- 三天打鱼，两天晒网 sāntiāndǎyúliǎngtiānshàiwǎng to work in fits and startsLiterally "to fish for three days and sun-dry the nets for two days"; describes a lack of perseverance or consistency in one's work or studies.
- 两三天 liǎngsāntiān two or three daystwo or three days; a very short period of time