We mean that his native language, not one that he's acquired subsequently, but the one that he learned as a child, was Greek, some version of the Greek language.

我们以他的母语为依据,即他们非后天习得的,而是从小所学的语言,即是希腊语的,或是一些希腊地区的方言的

耶鲁公开课 - 古希腊历史简介课程节选

As Melanie Phillips reported in the British Spectator in April, Gaubatz stated that he subsequently learned from CIA, British and Iraqi intelligence agents that the sites were stripped by Iraqi, Syrian, and Russian operatives who moved their contents to Syria.

CENTERFORSECURITYPOLICY: El-Baradei's nuclear policy

Mr Blythe, who was subsequently bailed, said he had only learned about the fan's death, and the resulting prosecution, when he was arrested.

BBC: Randy Blythe: Czech court acquits Lamb of God singer