问

Outer 门 — the gate radical (simplified from 門 in 1956), indexing radical for 问. Pictographically a pair of doors hinged on either side. The traditional 問 was filed under 口 (mouth), but the simplified character is indexed under 门. Supplies the sound too (mén → wèn, an old labial-initial shift visible across the men/wen pair, e.g. 闻).

Inner 口 — the mouth doing the asking. Together with the gate above the picture is famously evocative: a mouth at someone's door, calling out a question. Same speech-action 口 found in 吃, 喝, 叫, 听 — but here it is the semantic core rather than the indexing radical, since 门 took over indexing in the simplified form.