头一段的引言描绘出中世纪前期的英格兰景象。

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

《牛津词典》

它建于19世纪后期，20世纪前期。

It was built in the latter part of the 19th century and the early part of the 20th century.

youdao

这要追溯到B.F.斯金纳,一位活跃在上世纪前期的心理学家

This refers--this actually goes back to B.F. Skinner, a psychologist who flourished in the first half of this century.

youdao

This refers--this actually goes back to B.F. Skinner, a psychologist who flourished in the first half of this century.

这要追溯到B.F.斯金纳,一位活跃在上世纪前期的心理学家

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