Mrs. Green lives in the country, and she doesn't know London very well. One day, she went to London. She couldn't find her1Just then, she2a man near the bus stop. " I can ask him the way." she says to3and asked, "Excuse me, will you please4me the way to King Street?" The man smiled with5answers. He 6know English. He spoke Russian. He was a 7Then he8his hand into his pocket,9a piece of paper and let her10it. On the paper are these words, "Sorry, I don't speak English."

把多项式x²﹣x分解因式，得到的因式是（　　）

Ⅰ搜集资料：A：全脂奶粉含有蛋白质、脂肪和蔗糖等成分，脱脂奶粉含有高蛋白质、低脂肪等成分．B：假冒脱脂奶粉有两种：一是用全脂奶粉冒充脱脂奶粉，二是用淀粉冒充．

Ⅱ鉴定是否用淀粉冒充：取少量样品配成溶液，____．

Ⅲ鉴定是否用全脂奶粉冒充：①____；②____．

Ⅳ通过以上鉴定，我们还不能完全肯定是正宗的脱脂奶粉，还需对其____含量进行检测．