4 minutes ago, Genady said:

I've answered that one correctly, because I don't know much about formal grammar. So, I thought about the term, preposition. It has position in it. Aha, said I, it has something to do with space and time.  

Don't sell yourself short. Intuition is a factor in this.  

Funny how data pop up in your mind. I've just looked at a map of Russia, and the story of the building of St. Petersburg came to my mind, and how it was meant to obtain a north-western port by Peter the Great, and the human sacrifice it took. That would have given me a better chance at the question, but it didn't come to me when I was trying to answer it. I would have remebered it is NW of Moscow.

30 minutes ago, joigus said:

north-western port by Peter the Great

In my case, I knew too well where it is. That made me answer incorrectly.