✔ 最佳答案
你好.
本人原本是想解答你的问题的.不过细看之下,发现你的问题根本就有错,不应该是"When did he like doing when he was young? ",而是
"What did he like doing when he was young?"
因为既然你说了"when he was young",就不可以用表示时间的"when"提问.本人对纠正后的问题回答如下(其实他们都答了):
He liked both collecting stamps and listening classical music when he was young.