He retired because tennis is simply no longer his primary interest.

Since that was one of my primary interests, I dropped the story.

Usually, the primary interest is to get some chicken for the dinner.

His primary interest at the observatory was in solar research.

However, state formation became a primary interest in the 1970s.

This decision making process if the primary interest for the theorists.

This does not pose a problem; since only changes in energy are of primary interest.

They play by the rules of economic development, this is their primary interest.

I can see that food is not your primary interest here.