如图反映的是小刚从家里跑步去体育馆，在哪里锻炼了一阵后又走到文具店去买笔，然后走回家，其中x表示时间，y表示小刚离家的距离．根据图象回答下列问题：

对于函数$y=\sqrt{2x-1}$，当自变量x=2.5时，对应的函数值是（　　）

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     Today is June 1st.It's 1^.My friends and I like to play sports2Children's Day. We 3 May Day on May 1st.My mum and dad 4 to stay at home on that day. National Day is on 5^.We go to the park on National Day. The Spring Festival is6 January 7February. My family and I eat 8 during that holiday. September 10th is 9.^.My classmates and I like to make cards for our 10 on that day.

Why can't the woman get good marks in history?

下列四个数中，是负数的是（　　）