At the age of twenty, he went to four talks about chemicals by the famous scientist Humphrey Davy.

二十岁时，他参加了著名科学家汉弗莱·戴维的四场关于化学的讲座。

The precocious child could read by the age of three.

这个早熟的孩子在三岁时就能阅读。

He mastered several languages by the age of twenty.

他在二十岁时掌握了几种语言。

She aspires to become a multimillionaire by the age of 30.

她立志在30岁之前成为一名拥有数百万资产的人。

He dreams of attaining financial independence by the age of 30.

他梦想在30岁时达到财务独立。

The program aims to make every child literate by the age of ten.

该计划旨在使每个孩子在十岁时都成为识字的。

By the age of six or seven, I mastered politics.

到六七岁时，我完全掌握了政治。

He was already well known as a pilot by the age of 24.

他24岁时就已经是有名的飞行员了。

And by the age of ten learned to speak and read lips.

到十岁时，她学会了说话和读唇语。

It is not by the grey of the hair that one knows the age of the heart.

白发多少不能告诉你一个人心灵的年龄。