Inner joins are implicit if you create a proper DBML. Create the file and add the selected tables. Make sure the relationships are there per your joins above. Your code will be similar to the following:
YourDataContext dc = new YourDataContext();
var languages = dc.lkpxrfGeoCountryLanguageTactics.lkpGeoCountries.Select(c=>c.lkpGeoLanguage.languageName).Distinct();
Cheers.