①取口腔上皮细胞②擦干净载玻片和盖玻片③盖盖玻片④把从口腔内取出的碎屑涂在载玻片的水滴中⑤在载玻片中央滴一滴生理盐水⑥滴碘液染色
（Ⅰ）求角A；
（Ⅱ）求函数y=2sin2B+cos C−2B2 的最大值．
It's small and yellow.
——Thousands of people come to visit Qinghai Lake every year. ——That's true. It has become our _______.
