一日为师，
终身为父 | yī rì wéi shī ,
zhōng shēn wéi fù | lit. teacher for one day, father for ever (idiom) |
| 一时半刻 | yī shí bàn kè | a short time; a little while |
| 一时半晌 | yī shí bàn shǎng | a short time; a little while |
| 一时半会 | yī shí bàn huì | a short time; a little while |
| 一时半会儿 | yī shí bàn huìr | a short time; a little while |
| 一时半霎 | yī shí bàn shà | a short time; a little while |
| 一暴十寒 | yī pù shí hán | one day's sun, ten days' frost (idiom, from Mencius); fig. to work for a bit then skimp; sporadic effort; short attention span |
| 一曝十寒 | yī pù shí hán | one day's sun, ten days' frost (idiom, from Mencius); fig. to work for a bit then skimp; sporadic effort; lack of sticking power; short attention span |
| 一更 | yī gēng | first of the five night watch periods 19:00-21:00 (old) |
| 一会 | yī huì | a moment; a while; in a moment; also pr. [yi1 hui3] |
| 一会儿 | yī huìr | a while; also pr. [yi1 hui3 r5] |
| 一月 | yī yuè | January; first month (of the lunar year) |
| 一月份 | yī yuè fèn | January |
| 一望无垠 | yī wàng wú yín | to stretch as far as the eye can see (idiom) |
| 一望无际 | yī wàng wú jì | as far as the eye can see (idiom) |
一朝被蛇咬，
十年怕井绳 | yī zhāo bèi shé yǎo ,
shí nián pà jǐng shéng | once bitten by a snake, ten years in fear of a well rope; once bitten, twice shy (idiom) |
| 一本万利 | yī běn wàn lì | small capital, huge profit (idiom); to put in a little and get a lot out |
| 一杯羹 | yī bēi gēng | lit. a cup of soup; fig. to get part of the profits; one's share of the action |
| 一东一西 | yī dōng yī xī | far apart |
| 一板一眼 | yī bǎn yī yǎn | lit. one strong beat and one weak beats in a measure of music (two beats in the bar) (idiom); fig. follow a prescribed pattern to the letter; scrupulous attention to detail |
| 一板三眼 | yī bǎn sān yǎn | lit. one strong beat and three weak beats in a measure of music (four beats in the bar) (idiom); fig. scrupulous attention to detail |
| 一根筋 | yī gēn jīn | stubborn; inflexible; one-track minded |
| 一杆进洞 | yī gān jìn dòng | (golf) hole in one |
| 一条心 | yī tiáo xīn | to be of one mind; to think or act alike |
| 一次函数 | yī cì hán shù | linear function (math.) |
| 一次又一次 | yī cì yòu yī cì | repeatedly; over and over again |
| 一次性 | yī cì xìng | one-off (offer); one-time; single-use; disposable (goods) |
| 一次方程式 | yī cì fāng chéng shì | linear equation (math.) |
一次生，
两次熟 | yī cì shēng ,
liǎng cì shú | unfamiliar at first but you get used to it; strangers are first meeting, but soon friends; an acquired taste |
| 一步 | yī bù | (single) step |
| 一步一个脚印 | yī bù yī gè jiǎo yìn | one step, one footprint (idiom); steady progress; reliable |
| 一步登天 | yī bù dēng tiān | reaching heaven in a single bound (idiom); (esp. with negative: don't expect) instant success |
| 一氧化二氮 | yī yǎng huà èr dàn | nitrous oxide N2O; laughing gas |
| 一氧化氮 | yī yǎng huà dàn | nitric oxide |
| 一氧化碳 | yī yǎng huà tàn | carbon monoxide CO |
| 一决雌雄 | yī jué cí xióng | to have a show-down; to fight for mastery; to compete for a championship |
| 一波三折 | yī bō sān zhé | calligraphic flourish with many twists; fig. many twists and turns |
一波未平，
一波又起 | yī bō wèi píng ,
yī bō yòu qǐ | before the first wave subsides, a new wave rises (idiom); a new problem arises before the old is solved; many twists and turns to a story; one thing after another |
| 一派谎言 | yī pài huǎng yán | a pack of lies |
| 一流 | yī liú | top quality; front ranking |
| 一清二白 | yī qīng èr bái | perfectly clean; blameless; unimpeachable (idiom) |
| 一溜烟 | yī liù yān | like a wisp of smoke; (to disappear etc) in an instant |
| 一潭死水 | yī tán sǐ shuǐ | a pool of stagnant water; stagnant or listless condition |
| 一无所有 | yī wú suǒ yǒu | not having anything at all (idiom); utterly lacking; without two sticks to rub together |
| 一无所闻 | yī wú suǒ wén | unheard of |
| 一无所长 | yī wú suǒ cháng | not having any special skill; without any qualifications |
| 一无是处 | yī wú shì chù | not one good point; everything about it is wrong |
| 一生一世 | yī shēng yī shì | a whole lifetime (idiom); all my life |
| 一甲子 | yī jiǎ zǐ | sixty years |
| 一百一 | yī bǎi yī | faultless; impeccable |
