Marina Gray of Portland cracked the top 10 in the Miss USA pageant Monday night, surprising doubtful TV commentators by surviving two rounds of elimination. Gray, 23, won the title of Miss Maine USA last November and traveled to Shreveport, Louisiana, for the Miss USA competition. When she made the first cut, which whittled the 51 contestants down to just 15, the commentators who were narrating the live, on-air event called it a big surprise. A sergeant in the Maine Army National Guard, Gray had never considered entering a pageant until about two years ago when she read that an Army Reserve officer, Deshauna Barber, had won Miss USA. Making the first cut Monday night advanced her to the swimsuit competition, during which commentators noted her athletic, muscular build as she walked the runway in a floral bikini.