These rocks have been dated radiometrically at two billion years old.

经辐射能探测，这些岩石形成于20亿年前。

《牛津词典》

At 20 years old he was not as strong, as fast, as agile as he is now.

在他20岁时，他没有现在这样强壮、迅速、敏捷。

《柯林斯英汉双解大词典》

She was 15 years old at the time and lied about her age to get a marriage licence.

她当时只有15岁，为了拿到一个结婚证而在年龄上撒了个谎。

《柯林斯英汉双解大词典》

He was eighty-nine years old. At his funeral, many family members and friends honored him by wearing red clothes.

VOA: special.2009.03.22

It's late for some personal reasons as well. Milton had been, as you know, anticipating writing this poem since he was at least nineteen years old.

也有一些个人原因，你们知道，弥尔顿至少在19岁的时候就想要写这样一首诗了。

耶鲁公开课 - 弥尔顿课程节选

At this time, I also reconnected with my first boss when I was 15 years old.

这个时候，我也再次联系到了我15岁,时第一个老板。

斯坦福公开课 - Twitter之父Jack.Dorsey演讲：好奇和灵感的力量课程节选

The founders of the Navy Memorial envisioned this Lone Sailor at 25 years old at most, a senior second class petty officer who is fast becoming a seagoing veteran.

FORBES: Occupy Wall Street - Navy Veteran Expresses His Support

Tammy Andreycak was that person and she realized she had done something wrong and at 42 years old (at the time) and a single parent, she needed to come clean.

FORBES: Le-Nature's Final Prison Tally

When I first became a department manager at 25 years old, everyone on my staff was at least 10 years older than me.

FORBES: The Four Things Young Leaders Must Do to Effectively Lead Older Generations