题目

关于x的一元二次方程x2﹣4x+m＝0的两实数根分别为x1、x2，且x1+3x2＝5，则m的值为（ ） A．              B．               C．              D．0 答案：A 【分析】根据一元二次方程根与系数的关系得到x1+x2＝4，代入代数式计算即可． 【解答】∵x1+x2＝4， ∴x1+3x2＝x1+x2+2x2＝4+2x2＝5， ∴x2＝， 把x2＝代入x2﹣4x+m＝0得：（）2﹣4×+m＝0， 解得：m＝， 故选：A．I first visited hutong as part of a tourist group several years ago. We rode on a trishaw（脚踏三轮车） with a guide explaining the history, architecture and lifestyle of the local inhabitants. Having visited the "must-sees" of Beijing, like the Forbidden City, the Temple of Heaven, the Drum Tower and the Summer Palace, going into the hutong home of some famous ancient families gave the “Beijing experience” a human element. My curiosity has sharpened over the years from reading about them at every opportunity. During the preparation for the Olympics I was eager to learn that some siheyuan courtyards in hutong were turned into accommodations（食宿） for visitors. I wished to stay in one someday. Preparing for a recent trip to the capital, I eagerly sought one out. On my limited teacher’s salary, I settled on an affordable option, though I looked longingly at the more upscale courtyard accommodations. As usual, I ended up having something closer to a true experience. A real family still lives in the courtyard, which is closer to the original. The rooms all opened into the central courtyard. Flowers were blooming, beans and peas were climbing up the bamboo fence, and the cat was napping in the sun. Every day after exploring the city, I'd hurry back to the hutong, take a quick shower and join the cat – snoozing（小睡） in a bamboo-made chair with a book ready nearby. As the other guests came back we’d greet one another. There was a mother and young daughter from France, a guy from Canada, a mother and teenage daughter from the Netherlands, a teacher from England and several guests from various parts of China. Coming and going through the narrow alleys（小巷） of the hutong, the residents would smile and give cheery “ni hao” （hello）. Laughing children were playing under the watchful eyes of the neighbors. I felt right at home in this friendly neighborhood. 1. The main idea of the passage is about ______________. A．hutong days realize my desires to live local life B．Trishaw is the only way to visit the hutong C．living in the hutong with other visitors D．exploring the deeper of Beijing 2. When did the author have the idea to visit Beijing hutong? A．As early as he was a little child B．when he was reading the text books at school C．during the preparation for the Olympics D．the author doesn’t mention it specifically 3. The underlined word “upscale” in the fourth paragraph means _________. A．inexpensive B．high-class C．appropriate D．secondary 4. What is the impression of the author about the people in hutong? A．They came from all over the world. B．They all wanted to enjoy the old life of Beijing. C．They are living together in harmony. D．They are living in a heavenly peace life.