题目

如图，平行四边形ABCD中，AB＝3cm ， BC＝5cm ， ∠B＝60°，G是CD的中点，E是边AD上的动点，EG的延长线与BC的延长线交于点F ， 连结CE ， DF ． （1） 求证：四边形CEDF是平行四边形； （2） 当AE＝cm时，四边形CEDF是矩形．（直接写出答案，不需要说明理由） 答案：证明：∵四边形ABCD是平行四边形， ∴CF∥ED， ∴∠FCG＝∠EDG， ∵G是CD的中点， ∴CG＝DG， 在△FCG和△EDG中， {∠FCG=∠EDGCG=DG∠CGF=∠DGE∴△FCG≌△EDG（ASA） ∴FG＝EG， ∵CG＝DG， ∴四边形CEDF是平行四边形； 【1】3.5阅读理解 All of us have felt pain, which can take complete control of our body and mind, making it impossible to move and even to think. Yet we need pain, without which we wouldn't know if we have hurt ourselves. It is our body's warning system, which tells us that we are injured and should do something about it.     Pain is the most common reason we go to a doctor or other healer. It is the most common reason we take medicine. Until recently, however, most doctors knew of only a few drugs that stopped some pains. They knew little about the process of pain itself, about which, however, new knowledge is helping them learn to control pain better.     Scientists have learned that the sense of pain is made up of both chemical and electrical signals, which travel from nerve cells (神经细胞) in the injured area, up the central nervous system to the brain. And back down again. Scientists also have learned that the nervous system sends two different kinds of pain message to the brain, one very fast, and the other slow.     The first message is warning signal, which moves at a speed of 30 meters a second, and which travels to the middle part of the brain, and then to the outer part. In less than a second, the brain understands what part of our body is hurt and how badly it is injured. At a speed of only one meter a second moves the other message, which is the first step in the healing process, in which an important part is played by a very powerful material called prostaglandin, which are produced in almost every part of our body when needed. Scientists say prostaglandin raise and lower blood pressure, and also cause fever. When we hurt ourselves, the injured part produces a chemical that changes into prostaglandin, which cause the injured part to become red and swollen. and send the second, slower message of pain to the brain, which tells us not to use the injured part until it heals. 1．In your opinion, the word “healer” in the passage refers to someone who isn't a _____________but much like him or her.     A. nurse     B. patient     C. doctor     D. chemist 2．The English “________ ” in the passage can be translated into the Chinese “中枢神经系统”.     A. central nervous system     B. a powerful material     C. the nervous system     D. body's warning system 3．Why does the brain know very well that we have hurt ourselves, and even what part of our body is hurt and even how it is injured, in less than a second? Because as soon as we hurt ourselves the warning signals will travel at once, at a speed of________ from nerve cells in the injured areas, up our central nervous systems to the middle and then to the outer part of our brains.     A. 180 kilometers an hour     B. 180 meters a minute     C. 108 kilometers an hour     D. 108 meters a minute 4．Which of the following is true according to this passage?     A. All doctors can take complete control of pain in different ways.     B. Pain can control our body and mind completely.     C. Prostaglandin, the most common drug, is known everywhere.     D. Our injured parts can be used freely until they heal. 5．Which of the following has the same meaning as “when needed” in the passage?     A. In need of.     B. If it needs.     C. As it needed.     D. If necessary.