整个句子是：Emily was already singing and playing piano by age two.
问题描述：
整个句子是：Emily was already singing and playing piano by age two.
请问by age
答
age 2就是两岁时的意思,by age 2 就是：
Emily在2岁时就能唱歌弹钢琴.by 这个介词就是“在”的意思吗？是的，这里也可以理解为到两岁时。