The clock struck eleven at night. The whole house was quiet. Everyone was in bed except me. Under the strong light, I looked sad before a huge pile of troublesome stuff that were called “books”. I was going to have my exam the next day. "When can I go to bed?" I asked myself. I didn't answer; as a matter of fact, I dared not.

    The clock struck twelve. "Oh, dear!" I cried, "five more books to read before I can go to bed!” We pupils are the poorest in the world. Dad does not agree with me on this. He did not have to work so hard when he was a boy.

    The clock struck one. I was quite hopeless now. I forgot all I had learnt. I was too tired to go on. I did the only thing I could. I prayed, “Oh, God! Please help me pass the exam tomorrow. I do promise to work hard afterwards, Amen.” My eyes were so heavy that I could hardly open them. A few minutes later, with my head on the desk, I fell asleep.

先化简，再求值：（$\frac{x}{x+y}$﹣$\frac{x^2}{x^2+2xy+y^2}$）÷（$\frac{x}{x+y}$﹣$\frac{x^2}{x^2-y^2}$），其中x=$\sqrt{2}$，y=1．

据图，下列说法正确的是（）

如图所示，将塑料绳一端扎紧，把绳尽可能撕成更多的细丝，用手从上向下捋几下，观察到细丝蓬散开来，是因为细丝与手摩擦后带上____ （选填“同”或“异”）种电荷而相互____ （选填“排斥”或“吸引”）。