单项选择题 根据短文回答 46～50 题。 The Roadrunner The roadrunner(走雀)lives in the desert zone of the southwestern United States and northern Mexico.___________ (46)People gave it its name because they Usually see it running across a road,but of course,it spends more time among the plants of the desert than it does on roads.The roadrunner is quite a large bird-about 45 centimeters long and 25 centimeters high.___________(47)It holds its head straight out in front and its tail sticks straight。Out in back.It takes long steps and can run 30 kilometers an hour.It eats an amazing variety of food.Although it eats plants once in a while,it is mostly a meat eater.Most of its diet is insects,but it also catches birds,mice。and other smile animals.It is even brave enough to catch snakes and black widow spiders(蜘蛛) ___________ (48)When he finds one,he gives her presents-a snake to eat or a tiny branch of a tree to use in building a nest.Then they build their nest,the female lays eggs,and they raise their young.___________ (49) one couple in Arizona feeds a pair of roadrunner that come once at a time every day and make a noise outside the window.If Someone doesn't give the bird a piece of hamburger immediately, the bird knocks on the window with its beak (喙).Roadrunners are not shy.___________ (50)They will stand on a chair or table and watch television and they seem really interested in what is happening on the program.（ ） A．Roadrunners can also become friendly with people.B．People laugh when it runs because it looks so funny.C．It is a bird,but it can only fly about as much as a chicken can.D．In early spring.the bird doesn't eat anything.E．Another couple feeds a pair of roadrunners that go right into the house.F．In the spring,a male roadrunner begins looking for a female as a mate. 第 46 题 请选择（46）处的最佳答案

未知题型 某冶金工作者对锰的溶化点作了4次试验，结果分别为(单位：℃)1 269、1 271、1 263、1 265，假定数据服从正态分布，在α=0．05条件下，试检验： ①该工作者对锰溶化点的测量的平均结果是否符合于公布的数字1 260℃； ②侧量结果的标准差是否大于2℃．

单项选择题 根据短文回答 31～35 题。 Characteristics of PublicityPublicity offers several benefits.There are no costs for message time or space。An ad in prime-time television may cost$250.000 to$500.000 0r more per minute。whereas a five-minute report on a network newscast would not cost anything.However, there are costs for news releases,a publicity department,and other items.As with advertising,publicity reaches a mass audience.Within a short time。new products or company policies are widely known.Credibility about messages is high,because they are reported in independent media.A newspaper review of a movie has more believability than an ad in the same paper, because the reader associates independence with objectivity Similarly, people are more Likely to pay attention to news reports than to ads.For example.The Women's Wear Daily has both fashion reports and advertisements.Readers spend time reading the stories,but they flip through(浏览)the ads.Furthermore,there may be l o commercials during a half-hour television program or hundreds of ads in a magazine.Feature stories are much fewer in number and stand out clearly.Publicity also has some significant limitations.A firm has little control.over messages,their timin9,their placement,or their coverage by a given medium.It may issue detailed news releases and find only portions cited by the media；and media have the ability to be much more critical than a company would like.For example in l 982。Procter Gamble faced a substantial publicity problem over the meaning of its 123-year-old company logo(标志).A few ministers and other private citizens believed that the symbol was sacrilegious(亵渎的).These beliefs were covered extensively by the media and resulted in the firm receiving 1 5.000 phone calls about the rumor in June alone.To combat this negative publicity, the firm issued news releases featuring prominent clergy(神父)that refuted(消除)the tumors,threatened to sue(控告)those people spreading the stories,and had a spokesperson appear on Good Morning America.The media cooperated with the company and the false rumors were temporarily put to rest.However, in l 985。negative publicity became so disruptive that Procter& Gamble decided to remove the logo from its products.A firm may want publicity during certain periods.Such as when a new product is introduced or new store opened。but the media may not cover the introduction or opening until after the time it would aid the firm.Similarly, the media determine the placement of a story：it may follows a report on crime or sports.Finally, the media determine whether to cover a story at all and the amount of coverage to be devoted to it.A company-sponsored jobs program might go unreported or receive three-sentence coverage in a local newspaper. 第 31 题 The word 'mass'in Line 5 could best be replaced by（ ）.A．grouped.B．crowded.C．gathered.D．large.