题目

When other nine-year-old kids were playing games, she was working at a petrol station. When other teens were studying or going out, she struggled to find a place to sleep on the street. But she overcame these terrible setbacks (挫折) to win a highly competitive scholarship and gain entry to Harvard University. And her amazing story has inspired a movie, “Homeless to Harvard: The Liz Murray Story”, shown in late April.Liz Murray, a 22-year-old American girl, has been writing a real-life story of willpower and determination. Liz grew up in the shadow of two drug-addicted parents. There was如图，等边△ABC的边长为6，AD是BC边上的中线，M是AD上的动点，E是AC边上一点，若AE=2，EM+CM的最小值为 ．