题目

阅读理解 Itwas the first snow of winter—anexciting day for every child but not for most teachers. Upuntil now, I had been able to dress myself for recess(课间休息), but today I would need some help. MissFinlayson, my kindergarten teacher at Princess Elizabeth School near Hamilton,Ontario, had been through first snow days many times in her long career, but Ithink she may still remember this one. Imanaged to get into my wool snow pants. But I struggled with my jacketbecause it didn't fit well.It was a hand-me-down from my brother, and it made me wonderwhy I had to wear his ugly clothe判定方程x2-x•cos30°+cos60°=0的实数根情况．答：    ．