在三十年前的早春，圣海伦斯山开始轰鸣。

In the early spring three decades ago, Mount St. Helens began to rumble.

youdao

随着细胞的死亡，有些人大脑前部和侧部的收缩，在三十多岁时就能观察到，但是也有些人直到六七十岁依然不明显。

Contraction of front and side parts as cells die off was observed in some subjects in their thirties, but it was still not evident in some sixty and seventy-year-olds.

youdao

我们需要在三十天内付款。

We'll be needing payment within 30 days.

youdao

The U.S. was practically the last country to copy this system because, in the 1930s, because it didn't sound American.

美国几乎算是最后一个效仿此体系的国家,因为在上世纪三十年代。

耶鲁公开课 - 金融市场课程节选

There's a term paper which i'll talk more about as the weeks go on that's also worth 30% of the grade.

随着课程的进行我会在讲到学期论文,这也占成绩的百分之三十

耶鲁公开课 - 生物医学工程探索课程节选

Some of those kids will need coronary bypass surgery in their twenties; some of them will be blind by the time they're thirty.

这些孩子有的要在二十多岁时,做冠状动脉搭桥手术,有些人在三十岁的时候会失明

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选