The custom of choosing a sweetheart on this date spread through Europe in the Middle Ages, and then to the early American colonies.

中世纪时，在这个日子里选择意中人的习俗传遍了欧洲，然后又传到了早期的美洲殖民地。

youdao

The opening paragraph invokes a vision of England in the early Middle Ages.

头一段的引言描绘出中世纪前期的英格兰景象。

《牛津词典》

The theory: the theory here is that the early Middle Ages never existed and we have been counting the earth almost 200 years older than it actually is.

理论：这个理论认为中世纪的早期是从未存在过的，我们所计算的年份比地球实际年份提前了200年。

youdao

Roland Priebe encouraged his son Luke to graduate early because regular middle- and high-school classes were a bad fit for his academically gifted son.

WSJ: High School, in Three Years

And when I first heard - I heard about in the middle - in the early morning hours Monday, and I shed a tear.

NPR: 17 min 50 sec

To be a middle-middle-class American in the early 21st century is to occupy the 99.99 percentile of human existence, in terms of nutrition, wealth and ease.

FORBES: Digital Rules