他四岁时，开始学手风琴的翻译：When he was four years old, began studying accordion 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

When he was four, started learning the accordion

When he was four years old, began studying accordion

When his four years old, starts study the accordion

When he was 4 years old, started to learn accordion

When he was four years old, began studying accordion