when I was a child
彼は子供のとき日曜日によく釣りに行ったものです。
When he was a child, he would often go fishing on Sundays.
彼が日本に来たのは子供のときでした。
He came to Japan when he was a child.
子供のときからジムとは知り合いだ。
I've known Jim since I was a child.
私は子供のときでも上手に泳げた。
I could swim well even when I was a child.
彼らは子供のときからお互いに知っている。
They have known each other since they were children.
彼とはお互い子供のときからつきあっている。
We've been together since we were both kids.