题目

平面内有k条直线，其中任何两条直线不平行，任何三条不共点，设k条直线的交点个数为f（k），则f（k+1）与f（k）的关系是…（    ）A.f（k+1）=f（k）+k-1                            B.f（k+1）=f（k）+k+1C.f（k+1）=f（k）+k                              D.f（k+1）=f（k）+k+2 答案：解析：在k条直线的基础上增加一条即第k+1条直线，该直线与前k条直线每条有1个交点，共增加k个交点，故f（k+1）=f（k）+k.答案：CRecently the barbican museum in London held an exhibition called the rain room. During the time this exhibition was open, my twitter stream was filled with photos of people standing in the rain room, accompanied by the caption “rain room@ the barbican!” and a location attachment to prove that they were indeed in the rain room.This got me thinking. What were people actually saying by Tweeting about their visit? I think all they were doing was fulfilling the obligation that we have to share. Not sharing in the sense of treasuring a moment with people close to us, but sharing in the sense of “tell the world that I am doing a thing”.It’s not sharing; it’s showing off. When we log in to Facebook or Twitter we see an infinitely updating stream of people enjoying themselves. It’s not real life, because people only post about the good things whereas all the dull or deep stuff doesn’t get mentioned. But despite this obvious fact, it subconsciously makes us feel like everyone is having a better time than us.This is the curse of our age. We walk around with the tools to capture extensive data about our surroundings and transmit them in real-time to every friend we’ve made. We end up with a reduced understanding of reality because we’re more concerned about choosing a good Instagram filter(过滤器) for our meal than how it tastes.I don’t think that it’s inherently wrong to want to keep the world updated about that you’re doing. But when you go through life robotically posting about everything you do, you’re not a human being. You’re just a prism that takes bits of light and sound and channels them into the cloud.The key thing to remember is that you are not enriching your experiences by sharing them online; you are detracting from them because all your efforts are focused on making the look attractive to other people. Once you stop seeing things through the eyes of the people following you on Twitter or Facebook or Instagram, you can make your experiences significant, because you were there and you saw the sights and smelled the smells and heard the sounds, not snapped a photo of it through a half-inch camera lens.1.What do we learn from the first two paragraphs?A. Rain Room exhibition received a large audience in London.B. Most of people feel obligated to share their experience with friends.C. Many people want to inform others of their experience by Tweeting.D. All people having gone to the Rain Room took pictures.2.It seems to the author that ___________.A. Facebook or Twitter is a good place where we share personal experienceB. people seldom show depressing stuff on the social networking websitesC. most of people tend to show off that they are having a better time than othersD. sharing experience on the social networking websites is not real life3.By talking of “a good Instagram filter for our meal” (Line 3-4, Para.4), the author wants to show _____________.A. we are surrounded by various tools to capture our daily dataB. we are more concerned about how our life seems to be to othersC. we transmit our experience immediately to everybody we knowD. we gain more extensive perception of reality with digital tools4.What suggestion does the author give in the last paragraph?A. Enrich your experiences by sharing them online.B. Make efforts to make your life attractive to others.C. Stop showing your personal experience.D. Record the details of what you see, smell and hear.