Update to Lesson 17 on the Greek Present

I just added a short paragraph to the section on usage of the Greek present. Here’s what I added to the end of that section:

    What you can know for sure when you encounter a Greek present form is that the focus is not on when the action begins or ends. The Greek present form indicates imperfective verbal aspect. That is, it conveys a focus on the ongoing action, not on the beginning or end of the process.

This does not change anything I had already said. It just makes the connection to verbal aspect theory a little clearer.