设x1，x2是方程x2-x-1=0的两根，则x12+x22=（ ）
A．-3
B．-1
C．1
D．3
∵x1，x2是方程x2-x-1=0的两个实数根，
∴x1+x2=1，x1•x2=-1．
又∵x12+x22=x12+x22+2x1x2-2x1x2=（x1+x2）2-2x1x2，
将x1+x2=1，x1•x2=-1代入上式，
x12+x22=1-2×（-1）
=3．
故选D．
请仔细阅读下列文章，并根据所读内容在文章后的表格中的空格内填入一个最恰当的单词。 注意：请将答案写在答题卡上相应题号的横线上，每空只填一个单词。 When difficult people expresses themselves orally, they generally want at least two things: they’ve been heard and they’ve been understood. As a good communicator should be a good listener, five steps are advocated toward good listening. The first step is cooperating. How does a difficult person know that you’re listening and understanding? In fact, it’s through the way you look and sound while he is talking. You may help him to fully express his thoughts and feelings. You do this by nodding your head in agreement, making certain sounds of understanding. When the person begins to repeat what’s been said, it’s a signal of step two: turning back. It means that you repeat back some words he is using, sending a clear signal that you’ve listening carefully and that you think what he is saying is important. Having heard what he has to say, the next step is clarifying. At this point, you start to gather information about what is being communicated. Ask same open-ended questions, which will allow you to figure out what intention he is hoping to satisfy. The fourth step is to summarize what you’ve heard. This allows you to make sure that both you and the difficult person the same page. When you do this, two things happen. First, if you’ve missed something, he can fill in the details. Second you’ve shown that you’re making an effort to understand completely. This increases possibility of gaining cooperation from him. Having listened carefully, you’ve now arrived at the point of confirming with the person that he feels satisfied that his thoughts have been fully voiced. Ask if he feels understood. Then enough sincere listening, questioning, and remembering are brought together, understanding is usually achieved and a difficult person becomes less difficult and more cooperative.
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