Tone change. 一 is yī on its own. Before a fourth tone it becomes yí, and before the other tones yì. Textbooks write the change in, as here. How tone changes work
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Sentence #2938670 from Tatoeba · translation adapted
How 一旦 is built
Each colour is one part of the character. Parts repeat across thousands of characters, so learning them makes new words easier. See all 214 in our radicals chart.
一yīoneyí in 一旦
一 is a single shape of 1 stroke. Learn it whole, then watch its stroke order below.
Memory aidOne stroke for one, the way people once counted with rods.
旦dàndawn; daybreak
日sun · rì
一one · yī
How to write 一旦
一 1 strokes · 旦 5 strokes
Watch the order, then press Try writing it and draw each stroke in the grid. Each stroke is checked as you go.
Stroke order chart for 一旦 (yídàn). Red marks the next stroke, so you can copy it onto paper one step at a time.
一旦 (yídàn) means “once” or “as soon as”. It is an HSK 5 word.
Say it yídàn: yí with a 2nd tone, then dàn with a 4th tone. 一 is yī on its own. Before a fourth tone it becomes yí, and before the other tones yì. Textbooks write the change in, as here. Press Listen at the top of this page to hear it, or Slowly to hear each tone clearly.
Yes. 一旦 is written the same way in Simplified and Traditional characters.
Add a Chinese (Simplified) pinyin keyboard to your phone or computer, type yidan with no tone marks or spaces, then choose 一旦 from the suggestions. Typing yidan into this dictionary’s search box finds it too.
一旦 is an HSK 5 word in the HSK 2.0 word lists.
Turn words into conversations
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Sources: meaning and pinyin checked by a native Mandarin teacher against the official HSK lists. Extra meanings from CC-CEDICT (CC BY-SA 4.0). Example sentences from Tatoeba (CC BY 2.0 FR). Character parts and stroke order from Make Me a Hanzi.
一yí2nd tone, rising
旦dàn4th tone, falling
