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just as/the moment that
Definition
The grammar pattern "V(た形) + とたん(に)" is used to describe an unexpected change or event that occurs immediately after an action. This pattern is often translated to "just as" or "the moment that" and is used to convey a sense of suddenness or surprise. The speaker is describing an event that happens simultaneously with the action, but the speaker cannot control or plan the second event. This pattern is often used in situations where the speaker is describing a reaction or a consequence of an action.
Structure
| Form | Pattern | Example |
|---|---|---|
| Ta form | V(た形) + とたん(に) | 立ち上がったとたん、めまいがした。 |
| Ta form with た form of する | V(た形)するとたん、… | 窓を開けたとたん、強い風が入ってきた。 |
| Ta form with た form of する and に | V(た形)するとたんに、… | お酒を飲んだとたんに、顔が赤くなった。 |
Examples
立ち上がったとたん、めまいがした。
tachiagatta to tan, memai ga shita.
Just as I stood up, I felt dizzy.
立ち上がった (stood up) とたん (just as)、めまいがした (felt dizzy)
窓を開けたとたん、強い風が入ってきた。
mado o aketa to tan, tsuyoi kaze ga hairimashita.
Just as I opened the window, a strong wind came in.
窓を開けた (opened the window) とたん (just as)、強い風が入ってきた (a strong wind came in)
お酒を飲んだとたんに、顔が赤くなった。
osake o nomi ta to tan ni, kao ga akaku natta.
Just as I drank the sake, my face turned red.
お酒を飲んだ (drank the sake) とたんに (just as)、顔が赤くなった (my face turned red)
Context
This pattern is used to describe an unexpected change or event that occurs immediately after an action. It is often used in situations where the speaker is describing a reaction or a consequence of an action. The speaker cannot use their own intentional actions in the second half of the sentence.
Watch out
The speaker cannot control or plan the second event, so using an intentional action in the second clause is incorrect.
The 'ta' form is used to describe a completed action, so using the dictionary form instead is incorrect.
〜次第 is used to describe a planned sequence of events, while とたん(に) is used to describe an unexpected event.
Strategy
In the JLPT exam, this pattern is often tested in the reading comprehension section. Be careful to identify the correct usage of とたん(に) and avoid confusing it with other patterns.
In context
Worked examples drawn from JLPT N3 test-style questions. Each sentence shows V(た形) + とたん(に) used correctly, with a brief note on what the pattern is doing.
立ち上がったとたん、めまいがした。
Pattern used: とたん
'Ta totan' describes an immediate, unintentional reaction (dizziness) to an action (standing up).
窓を開けたとたん、強い風が入ってきた。
Pattern used: とたん
The wind entering is a sudden, automatic consequence of opening the window.
お酒を飲んだとたん、顔が赤くなった。
Pattern used: とたん
'Ta totan' emphasizes the instantaneous nature of the face turning red.
Interactive
立ち上がった______、めまいがした。
Adaptive practice
Our adaptive engine will quiz you on this grammar pattern and track your progress toward mastery.