She made her senior debut at Nationals and placed 7th. She was the third alternate for the 2007 World Championships, the 2007 World Junior Championships, and the 2007 Four Continents Championships.
This passage describes a competitor's achievements in various international championships.  She made her senior debut at Nationals, placing seventh. She was also a backup for other significant events like the World Championships, World Junior Championships, and Four Continents Championships.