What became of that friend of hers?

what 是疑问代词，表示"什么"，用于询问情况或状态。 became 是动词 become 的过去式，意思是"变成、成为"。 of 在这里表示"关于、属于"的关系，用于连接主语和所询问的对象。 what became of 是一个固定短语，意思是"...后来怎么样了"，用于询问某人或某物的后续情况或命运。