I have kept birds for some 30 years.

我养鸟大约有三十年了。

《柯林斯英汉双解大词典》

On turning 30: "I kind of feel like the same person except more time has gone by."

关于年届三十：“我觉得我没什么变化，只不过更多的时光流逝了。”

youdao

I think electricity will come in 30 minutes.

我想三十分钟之内电就会来了。

youdao

And as I mentioned before, death would occur in 20-30 percent of the cases that got the most severe form of smallpox.

就像我刚说的,百分之二十到三十的,天花重症病人会死亡

耶鲁公开课 - 生物医学工程探索课程节选

Monday evening will be the time at which the midterm exam will be posted on the website, and that'll be at 6:00 pm Monday evening. You'll have a 24-hour period of time in which to find--I forget what I said--30 or 40 minutes? It'll be clear on the instructions. To just sit and treat it as if you're in an in-class exam situation, and write your essay.

周一晚上期中考试的内容会,粘贴到网站上，应该是晚上六点,你可以在一天之内抽出30到40分钟完成考试0,这在说明上都写明了,就把它当作课堂考试对待，写一篇短论文。

耶鲁公开课 - 旧约导论课程节选

I should've been counting down--35, 30, 25 and so forth.

我应该在倒计时--35年，30年，25年等等。

耶鲁公开课 - 死亡课程节选

We are vulnerable to placebos: "Hey -- I took the 30-day free sample and I feel sure my vision did improve!"

CNN: Herbal remedies need real scrutiny

"I look at it as I pitched in 30-something games last year and I think we won 18 of my starts, " he said.

WSJ: Ankiel leads Astros over Yankees' split squad 7-6

By July I was doing 30-40 mile rides and by August I was doing them pretty hard, maintaining 18-19 miles per hour on the flat parts.

FORBES: In Praise Of (Mostly) Vegan Diets