Question: big events in season 7 of grey's anatomy

title: Grey's Anatomy (season 7)
text: The season follows the aftermath of season six shooting , in which Derek Shepherd ( Patrick Dempsey ) , Alex Karev ( Justin Chambers ) and Owen Hunt ( Kevin McKidd ) are shot , and a total of 11 people died . Cristina Yang ( Sandra Oh ) was the most affected by the shooting , quitting her job . Cristina and Owen later marry with `` her person '' , the show 's protagonist Meredith Grey ( Ellen Pompeo ) , as her maid of honor . Meredith and Derek start an Alzheimer trial , with Meredith suspecting that Richard Webber 's ( James Pickens , Jr . ) wife Adele ( Loretta Devine ) may have Alzheimer 's . Arizona Robbins ( Jessica Capshaw ) leaves for Africa after getting a grant leaving Callie Torres ( Sara Ramirez ) despondent . She sleeps with Mark Sloan ( Eric Dane ) and becomes pregnant by chance . Arizona returns , confessing her love for Callie . Meredith messes up the trial for the sake of Adele only to have Alex find out and tell Hunt , leading to Meredith kicking him out of her house . Derek leaves Meredith with Zola . Lexie Grey ( Chyler Leigh ) decides to give Mark a second chance but later starts a relationship with Jackson Avery ( Jesse Williams ) . Teddy Altman ( Kim Raver ) starts a relationship with Andrew Perkins ( James Tupper ) , a trauma counselor , but later falls for her patient , Henry Burton . 

Answer: answer: Cristina Yang was the most affected by the shooting, quitting her job.  Cristina and Owen later marry.   Meredith and Derek start an Alzheimer trial.  Arizona Robbins leaves for Africa, then returns, confessing her love for Callie.  Meredith messes up the trial for the sake of Adele only to have Alex find out and tell Hunt, leading to Meredith kicking him out of her house.  Derek leaves Meredith with Zola. Lexie Grey decides to give Mark a second chance but later starts a relationship with Jackson Avery.  Teddy Altman starts a relationship with Andrew Perkins.