N2 — outside your level filter
Modifies the end of the sentence directly and takes no だ／です, so there are no forms to conjugate.
いつの間に
itsunomaniwhen (did that happen) — without one noticingN2adverb
Example sentences2
いつの間にこんなに時間がたったのだろう。
itsu no ma ni konna ni jikan ga tatta no darou.
I wonder how so much time passed without me noticing. neutral
いつの間に宿題終わらせたの？早すぎ。
itsu no ma ni shukudai owaraseta no? hayasugi.
When did you even finish your homework? That's way too fast. casual