1. 询问;查询;打听
    An inquiry is a question which you ask in order to get some information.

    e.g. He made some inquiries and discovered she had gone to the Continent...
           他打听了一番，发现她已经去了欧陆。
    e.g. After a brief inquiry about the Christmas holiday, he returned to the subject of music.
           简短地问了一下圣诞假期之后,他又回到了音乐的话题上。

2. (官方的)调查,查问
    An inquiry is an official investigation.

    e.g. This is the most difficult and shocking murder inquiry I have had to open in the last 25 years...
           这是 25 年来我所展开的最困难、最令人震惊的谋杀调查。
    e.g. The Democratic Party has called for an independent inquiry into the incident.
           民主党要求对事件展开独立调查。

3. 询问(或调查)过程
    Inquiry is the process of asking about or investigating something in order to find out more about it.

    e.g. The investigation has suddenly switched to a new line of inquiry.
           调查突然转向了一条新的线索。

4. 协助警方调查
    If you say that someone is helping the police with their inquiries, you mean that the police are questioning them about a crime, but have not yet charged them with it.

    e.g. Two men were helping police with their inquiries at Salisbury last night.
           两名男子昨天夜里在索尔兹伯里接受了警方盘问。

5. see also: court of inquiry