Time: surprise

急に

急きゅうに means that something happened unexpectedly or quickly.

Example

急に電車が現あらわれた。 A train suddenly appeared.

ふと

This means “suddenly”, “unexpectedly”, “unintentionally”. Emphasis is on the lack of intention.

Example

ふと通とおりに１０００円を見みつけた。 I found 1000 yen on the street by chance.

たとたん

Means “just as”. Used for an action that happens just at the moment something else occurs. Can convey a nuance of something unexpected or surprising. Used with verbs in the past form (た).

Example

部屋へやを掃除そうじしたとたん、うちの猫ねこが吐はいてしまった。 As soon as I cleaned my room, my cat vomited.