investigation 
英 [ɪnˌvɛstɪˈɡeɪʃən]  美 [ɪnˌvɛstəˈgeɪʃən] 
n. 研究；调查

例句：
Many people have been subjected to an investigation through interview or questionnaire. 

很多人不得不通过访谈或问卷的形式接受调查。

He ordered an investigation into the affair. 

他下令对此事开展调查。

Investigations are continuing into the cause of his death. 

对于他死因的调查仍在继续。

He is under investigation for corruption. 

他因贪污腐败而受到调查。