C
research into对...研究：1)(作动词用)He is researching into the reading problems of young school children.2)（作名词用）to carry out a research(="some" research)into the causes of brain damage.(对大脑损伤原因进行研究)。研究可译为make researches into, make a study of 或直接用动词study vt或research into (a problem etc.).