题目

Dorothy was in a bit of a quandary (不知所措). She was undecided about whether she should go or not, but she had worn out all of her excuses. The only solution was to seek support, so she rang a friend. “I’m just going to the university to donate blood. What do you think? Does that sound like a good idea to you? ”After some communication and persuasion, Xiaohui agreed to go too. On arrival at the university clinic, they found about 20 other students also donating blood. Their primary task was to register with the nurse. She started by interviewing each of them for a few minu用配方法解一元二次方程x2+8x+7=0，则方程可变形为（ ）A．（x-8）2=16B．（x+8）2=57C．（x-4）2=9D．（x+4）2=9