I was making a study of them, for a while.

But the study itself could not be made for many years.

You may not know that, but I've been making a study of those things recently.

He had made a special study of the subject after all.

I have made a study of it for some years now.

"I made quite a study of them, and brought these along with me."

"You seem to have made a study of the problem."

"I will leave you the means to make a study."

He made a study of the names in the list.

No wonder he made such a study of Earth culture!