题目

如图，矩形OABC的顶点A在y轴上，C在x轴上，双曲线y=与AB交于点D，与BC交于点E，DF⊥x轴于点F，EG⊥y轴于点G，交DF于点H．若矩形OGHF和矩形HDBE的面积分别是1和2，则k的值为（ ） A．    B． +1     C．      D．2 答案：B【考点】反比例函数系数k的几何意义． 【专题】计算题． 【分析】设D（t，），由矩形OGHF的面积为1得到HF=，于是根据反比例函数图象上点的坐标特征可表示出E点坐标为（kt，），接着利用矩形面积公式得到（kt﹣t）•（﹣）=2，然后解关于k的方程即可得到满足条件的k的值． 【解答】解：设D（t，）Passage 3（2017·新课标卷III）Lots of people find it hard to get up in the morning, and put the blame on the alarm clock. In fact, the key to easy morning wake-up lies in resting your body clock. 1 Here’s how to make one.● 2 In order to make a change, you need to decide why it’s important. Do you want to get up in time to have breakfast with your family, get in some exercise, or just be better prepared for your day? Once you are clear about your reasons, tell your family or roommates about the change you want to make.● Rethink mornings. Now that you know why you want to wake up, consider re-arranging your morning activities. If you want time to have breakfast with your family, save some time the night before by setting out clothes, shoes, and bags. 3 That’s a quarter-hour more you could be sleeping if you bought a coffee maker with a timer.● Keep your sleep/wake schedule on weekends. If you’re tired out by Friday night, sleeping in on Saturday could sound wonderful. But compensating on the weekends actually feeds into your sleepiness the following week, a recent study found. 4 ● Keep a record and evaluate it weekly. Keep track of your efforts and write down how you feel. After you’ve tried a new method for a week, take a look at your record. 5 If not, take another look at other methods you could try.A. Get a sleep specialist.B. Find the right motivation.C. A better