At54 years of age, he didn't know that this would be his last symphony.
这是2020版高中英语北师大版必学第三册第7单元的句子。
这是一个经常见到的搭配，用于表示某人的年龄：
at54 years of age=at the age of 54
除以上常用表达外，还可以用：
at 54
at54 years old
补充例句：
At14 years of age, she became the younest player to compete at Wimbledon. 她14岁时成了参加温布尔顿比赛的最年轻的选手。
At78 years of age, he’s still undisputedleader of his country. 78岁时，他仍是他的国家公认的领袖。
比较：
Saulentered Yale at 19 years of age. 索尔19 岁考上了耶鲁大学。
Saulentered Yale at the age of 19. 索尔 19 岁考上了耶鲁大学。