The crime might not be serious, but at least it would lead to a line of enquiry.

What will you put forth as the subject of enquiry?

He did not yet want to be known as an agent of enquiry.

He must keep his head, and pursue a straight line of enquiry.

Letters of enquiry are not only useful for business people.

Attention to this principle makes all the difference in a process of enquiry.

The second question makes the same sort of enquiry about the relations between categories.

I will access other data that may be relevant to this line of enquiry.

On the other side we must assert freedom of enquiry.

The national authorities are responsible for this sort of enquiry.