题干

已知M=x2+y2﹣4x+2y,N=﹣5,若x≠2或y≠﹣1,则(   )

A:M>N

B:M<N

C:M=N

D:不能确定

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答案(点此获取答案解析)

A

同类题2

阅读下文,回答问题
一个富翁的梦
    从前,巴格达城里有个富翁,他拥有许多金钱和房产。但由于他不善经营,花钱大手大脚,很快就坐吃山空,成了一贫如洗的穷光蛋。
    一天晚上,有人托梦给他,说只要他去了埃及,就能富裕起来。于是,他就风尘仆仆赶到埃及,住进一家清真寺里。
    不想,有个窃贼在清真寺隔壁行窃时被人发觉,仓______(cāng  chāng)皇逃走了。巡警没抓到窃贼,却把这位巴格达人误当成贼,打过之后,投进了监狱。
    七天之后,省长亲自提审。倒霉的巴格达人就向省长讲述了他做的梦。省长听了哈哈大笑,说:“你可真蠢,我也曾做过三次这样的梦。那人对我说:巴格达城中心那个住宅的大花园的喷水池下面有宝藏______(zàng   cáng),让我去取。我才不相信这些哩。给你几块钱,快回巴格达吧。”
    巴格达人兴高采烈地回到家乡,因为省长讲的那个住宅正是他的家。回到家后,他立即去花园里找宝,终于刨出一只封了口的小坛子。他打开坛子,里面空空的,他不甘心,又伸手去摸,好不容易摸出一张字条,他取出来一看,上面有一行小字:
       勤俭是致富的根本挫折是进步的台阶
    巴格达人恍然大悟,明白了其中深刻的道理。第二天,他把______(惟一  唯一)的房屋也卖掉了,用卖掉得来的钱采购货物,去外地销售。他起早贪黑,精打细算,发展货源,拓宽销路,只几年______(工夫  功夫),就成了巴格达著名的富商。

同类题3

阅读理解。

    Holmes said, “Somebody sent a letter with five pips (桔核) in it from India, and arrived seven weeks later to kill John's uncle. Then they sent five pips from Scotland and arrived three days later to kill John's father. Now they have sent five pips to John from London!”

    “The letters are all from sea ports. The writer was on a ship when he wrote the letters,” I replied.

    “Very good, Watson! And John's enemy is in London already!”

    “Well, I hope they won't kill young John,” I said.

    But they did. The next morning, we read in the newspaper that a policeman found him die near Waterloo station. Holmes was very angry about it.

    “He came to me for help and those men murdered him! I'm going to find them, if it's the last thing I do!” he said to me, and he hurried out of the house.

    At night, when he came back, he was tired, but pleased, he said, “I know the names of John's enemies! And now I'm going to send them a surprise! This will frighten them!” He took five pips from an orange and put them in an envelope (信封). On it he wrote “S. H. for J. C.”

    “I'm sending the pips to captain James Calhoun. His ship is called the Star. He and his men are sailing back to Georgia, USA.”

    “How did you find him, Holmes?” I asked.

    “Ship's papers,” he said, “I've looked at hundreds of them today. Only one ship, the Star, was in the three ports at the right times, this morning the Star left London to sail back to Georgia. I found out that the captain and two of his men, all Americans, weren't on the ship last night, so I'm sure they killed John. When they arrive in America, they'll get the pips and then the police will catch them!”