题目

下列函数：①; ②; ③; ④,是二次函数的有:A.1个 B.2个 C.3个 D.4个 答案：【答案】C【解析】根据二次函数的定义，对每个函数进行判断，即可得到答案.解：①是二次函数，正确；②不是二次函数，错误；③整理得，是二次函数，正确；④整理得，是二次函数，正确；∴一共有3个二次函数；故选择：C. Can you imagine a five-year-old boy writing and playing music on a child-sized violin? This was true of Wolfgang Amadeus Mozart, a gifted boy who grew up to be one of the most creative composers (作曲家) of all time. Then you might think that the life of this child was easy all the time. Read on. Decide for yourself.Mozart was born in January of 1756 into a musical family. His father, Leopold Mozart, recognized the talent of his child and devoted himself to teaching him. Later, Mozart toured Europe, putting on concerts for the people of high social positions. He could listen to any piece of music once and then play it from memory. He could play the piano or the violin with his eyes covered. What's more, music that Mozart wrote at the age of five was as good as works by many adult composers.Mozart earned a living by selling his compositions, giving concerts and providing music lessons for the wealthy. Some of the operas Mozart wrote, such as The Marriage of Figaro, The Magic Flute and Don Giovanni, are still performed today. He composed 41 symphonies(交响乐). However, none of them earned him much money, and he spent far more than he was able to earn. Mozart often waited until the last moment to work on pieces that had been asked for.By the spring of 1791, Mozart was ill and sad. He was deeply in debt(债务). His health, which had never been good, was becoming even worse. A stranger asked Mozart to write a musical piece for a funeral( 葬 礼 ). Mozart agreed, but then began to fear that it was being written for his own death. His fears turned out to be true. Mozart died in December of 1791, at the age of 35.1.What is the purpose of the writer by saying "Read on. Decide for yourself "in paragraph1?A.To increase your reading interest.B.To tell you it is your business to read it or notC.To introduce that the child always led an easy life2.Which of the following can't show that Mozart was a born musician?A.He could play any music wonderfullyB.He could write good works at an early age.C.He held concerts for the people of high social positions3.We can infer from the paragraph 3 that________.A.Mozart could support himself by working so hardB.Mozart led a poor life although he wrote many piecesC.Mozart's compositions sold well and he made a lot of money4.According to the passage, which statement is TRUE?A.Mozart was still poor before his deathB.Mozart's fame gave him a hard life and he felt unhappyC.Mozart was in poor health so he wanted to wrote a piece for his own funeral5.What's the passage about?A.Mozart's lifetime B.Mozart's talent C.Mozart's works