How do Mormon missionaries learn foreign languages so quickly?

Latter-day Saints who choose to serve missions enter a Missionary Training Center for just 2-10 weeks before they go out into their assigned areas for the remaining 18 or 24 months. Since many serve in foreign countries, they learn a new language while in training, and many missionaries are fluent after about a year. What techniques are used to teach LDS missionaries, and how to they get away with doing so in such a short span of time? Would the LDS church claim that it's related to the gift of tongues?