Mozart was five when first wrote music, and by the age of six he had performed in front of the Emperor of Austria – twice!

莫扎特五岁时第一次创作音乐，六岁时他已经在奥地利国王面前表演过两次了！

So much so he taught himself French and English all by the age of 6.

所以他在6岁是就开始自学法语和英语了。

The average male heart becomes weaker with age, and by the age of 70 its power to pump blood around the body could have decreased by up to a quarter of its youthful strength.

一般情况下的心脏随着年龄增长而衰。到了70岁时，心脏向全身供血的能力最多可能减少为年轻时的3/4。

By the age of 14, he was fit enough to pose for anatomical charts.

在十四岁时，他已经够健壮到能当人体结构图的模特儿。

For instance, it is impossible not to be deeply moved by the ages of the fallen, as the gravestones in our war cemeteries remind us.

譬如，当我们伫立在战争公墓，凝视着墓碑上那些逝去之人的年纪，心中总会涌起难以言喻的动容。

By the age of three, he was able to read.

到三岁时，他已经识字了。

Each Indian of the Great Plains could ride a horse by the age of five.

大平原地区的每个印第安人五岁就开始骑马。

Here we have a 10-year-old boy with a strong jawline and overall good looking face...who went on to develop flat cheeks, a receded chin, a weak jawline and a slight hook in the nose by the age of 17.

这个十岁大的孩有着分明的下颌轮廓线和俊秀的面庞，后来，他在十七岁时，脸颊变得扁平，下巴开始回收，下颌轮廓线变得模糊，鼻子也开始有轻微弯曲。

This give-and- take allows them to use fluent sentences by the age of four.

这种“输入并输出”的方法让人类儿童在四岁时就能使用流利的句子。

The actor achieved fame by the age of 22.

那位演员22岁时就成名了。

We're on track for there to be more people over age 60 than under the age of 14 by the middle of this century.

按照目前的趋势，到本世纪中叶，60 岁以上的人口将会超过 14 岁以下的人口。

For both girls and boys, it is usually complete by the age of 18.

无论孩子还是女孩子，通常都是到 18 岁完成（青春期）。

Baldness affects approximately half of men worldwide by the age of 50.

全球大约有一半的在50岁时秃顶。

He had mastered both integral and differential calculus by the age of 15.

他在15岁时就已经掌握了微积分。

By the age of twenty-five, I had managed to get married ... and also divorced.

25岁时，我不仅完成了结婚这件大事，也经历了离婚。

Blood tests indicate that most children have had it by the age of 5.

血液测试表明，大多数儿童在5岁时就患有此病。

By the age of 14, he was playing internationally.

到14岁时，他开始在国际上下棋。

For both sexes, it is usually complete by the age of eighteen.

孩和女孩通常在18岁结束青春期。

Do you know he was a multimillionaire by the age of 35?

你知道他在35岁时已经是千万富翁了吗？

By the age of seven, children are capable of thinking in abstract terms.

【abstract】儿童到了七岁就具有抽象思维的能力。