 Complete the following phrase:  Burkas first significant achievement was at the 2003 IAAF World Cross Country Championships, where she won the bronze in the junior race. She made her first impact in senior athletics later that year when, following the Ethiopian federations refusal to allow Merima Denboba to compete, Burka took the womens race at the Lotto Cross Cup Brussels. She returned to Belgium the following year and repeated the feat. After becoming junior world champion in cross country running at the 2005 World XC Championships, she competed at the 2005 World Championships in Athletics to finish eighth in the 1500 metres race. A month later she won the bronze medal in 3000 metres at the 