Sarah: Hi, friends! My parents will have a birthday party for me.

Amy: Great! When is your birthday?

Sarah: It's on May 12th. It's my eleventh birthday. Will you come?

Amy: Yes！What about you, John?

John: What day is your birthday?

Sarah: It's Saturday. We have no classes.

John: OK. I'll come. Do you like sports?

Sarah: Yes, I do. I like playing football very much.

John: Good! I'll give you a surprising gift.

如图，小华准备在边长为1的正方形网格中，作一个三边长分别为4，5，$\sqrt{17}$的三角形，请你帮助小华作出来．

选出下列文学常识中表述不正确的一项  (       )

已知α是锐角，且点A（$\frac{1}{2}$，a），B（sinα＋cosα，b）， C（－m²＋2m－2，c）都在二次函数y＝－x²＋x＋3的图象上，那么a、b、c的大小关系是  　 （   ）