Katrina studied the russian language in high school. although not fluent, she did accumulate a large vocabulary. years later, she decided to go to russia, so she wanted to brush up on her vocabulary. she picked up the vocabulary much more quickly because:

She is exposed to an environment in which utilizing and practicing the language is a necessity when living in the particular society. By being exposed to such an environment allows her to become more used to the language, therefore her ability to pick up the language quickly is increased exponentially.