他的父亲是一位著名的历史学家。

His father was a famous ___historian.

我非常愿意帮助历史学家解开泰国起源之谜。

I would be very willing to help ___historians solve the enigma about the origin of Thailand.

这位历史学家发表了一项关于中世纪欧洲的开创性研究。

The ___historian published a groundbreaking study on medieval Europe.