Well, I can understand up to six languages but I can easily speak only four: greek (my own), english, dutch and finnish.
The thing is that the language I studied the longer besides greek is french. I studied for ten years but I never used it. While dutch, I studied on my own for a year or so and I can speak it (in every day situations) better. Because I lived in the Netherlands for three years and I made a pact to use it.