investigation

inquiry, investigation, research, survey

这些名词均有“调查”之意。
inquiry: 普通常用词，指正式调查，也指一般的打听或查询。
investigation: 一般指有系统的调查以得到希望发现或需要知道的事。
research: 指科学工作者等为揭示自然规律或获取某个领域的新知识而进行长时间的调查研究。
survey: 多指为写书面报告而进行的民意测验或调查。

名词 investigation:

1. an inquiry into unfamiliar or questionable activities
   同义词：probe
2. the work of inquiring into something thoroughly and systematically
   同义词：investigating

1. It's only the initiative of the investigation.
   这仅仅是调查的开始。
2. We were greatly aided in our investigation by the cooperation of the police.
   我们在调查的过程中得到警方的大力协助。
3. The investigation was carried out under the direction of a senior police officer.
   调查是在一位高级警官的指导下进行的。
4. He has promised a thorough investigation into the affair.
   他已答应彻查此事。
5. The government made an investigation of the employment in the public and private sectors.
   政府对国营和私营部门的就业情况作了一次调查。
6. The accident is under investigation.
   这一事故正在调查之中。