Question: When Middle Prut Valley is the land formation what is the highest of which currently forests, km² ?
SQL: SELECT MAX("of which currently forests, km²") FROM "1-19242-5" WHERE "land formation" = 'Middle Prut Valley';

Question: When 312 is  of which currently forests, km² what is the land formation? 
SQL: SELECT "land formation" FROM "1-19242-5" WHERE "of which currently forests, km²" = 312.0;