单选题 There is no question that the old style of air pollution could kill people. In one week following the infamous "peasouper" fog in December 1952, 4, 700 people died in London. Most of these people were elderly and already had heart or lung diseases. A series of these killer fogs eventually led to the British Parliament passing the Clean Air Act which restricted the burning of coal. Fortunately the effect of smog on the lungs is not so dramatic. Scientists have now conducted a number of laboratory experiments in which volunteers are exposed to ozone inside a steel chamber for a few hours. Even at quite low concentrations there is a reversible fall in lung function, an increase in the irritability of the lungs and evidence of airway inflammation (发炎). Although irritable and inflamed lungs are particularly seen in people with asthma (哮喘) and other lung diseases, these effects of ozone also occur in healthy subjects. Similar changes are also seen after exposure to nitrogen dioxide, although there is some disagreement about the concentration at which they occur. Other studies have found that people living in areas with high levels of pollution have more symptoms and worse lung function than those living in areas with clean air. Groups of children attending school camps show falls in lung function even at quite low concentrations of ozone. There is also a relationship between ozone levels and hospital admissions for asthma, both in North America and Australia. It is suspected that long-term exposure to smog may result in chronic bronchitis (支气管炎) and emphysema (肺气肿), but this has yet to be proven. Recently an association has been found between the levels of particles in the air and death rates in North American cities. The reason for this association is not understood and as yet there is no evidence this occurs in Australia. However, we do know that hazy days are associated with more asthma attacks in children.

单选题有5本不同的书，其中语文书2本、数学书2本、物理书1本。若将其随机地摆放到书架的同一层上，则同一科目的书都不相邻的概率是______

单选题设函数则f(x)在x=0处______．A．极限不存在B．极限存在但不连续C．连续但不可导D．可导

单选题在电炉上安装了4个温控器，其显示温度的误差是随机的．在使用过程中，只要有两个温控器显示的温度不低于临界温度t 0 ，电炉就断电，以E表示事件“电炉断电”，而T (1) ≤T (2) ≤T (3) ≤T (4) 为4个温控器显示的按递增顺序排列的温度值，则事件E等于______． A．{T (1) ≥t 0 } (13){T (2) ≥t 0 } C．{T (3) ≥t 0 } D．{T (4) ≥t 0 }

单选题设函数p(x)，q(x)，f(x)连续，而y1，y2，y3都是方程y"+p(x)y'+q(x)y=f(x)的解，则该方程必定还有解

单选题若两个等差数列{an}和{bn}的前n项和分别是Sn，Tn，已知，则等于______A．7B．C．D．E．5

单选题设矩阵满足AX+E=A2+X，则矩阵X=______。A．B．C．D．

单选题制鞋厂本月计划生产旅游鞋5000双，结果12天就完成了计划的45%，照这样的进度，这个月(按30天计算)旅游鞋的产量将为{{U}} {{/U}}． A.5625双 B.5650双 C.5700双 D.5750双 E.5800双

单选题设为向量组α1，α2，…，αm的一个线性无关的部分组，称为向量组α1，α2，…αm的一个极大线性无关组，如果(A)与α1，α2，…，αm等价．(B)向量组α1，α2，…，αm中至少还存在一个与有相同个数的线性无关的部分组．(C)与α1，α2，…，αm不等价．(D)α1，α2，…，αm中其余的每个向量都不可由线性表出．

单选题设函数将f(x)展成周期T=2l=4的余弦级数，其和函数为S(x)，则其余弦级数系数a0及S(-3)+S(4)的值分别是______A．0及．B．1及1．C．0及0．D．1及．

单选题有一圆形跑道，甲从A点、乙从B点同时出发反向而行，8分钟后两人相遇，再过6分钟甲到达B点，又过去14分钟两人再次相遇，则甲绕跑道跑一周需要______分钟．

单选题如图2.5.12所示，直径分别是15和5的两圆外切于某点，AB分别切两圆于A和B，则梯形AOO'B的面积与周长分别是()．

单选题设X为连续型随机变量，方差存在，则对任意常数C和ε＞0，必有______

单选题直线y=x+k与4y-2x-2k-1=0的交点在圆x2+y2=1的内部，则k的取值范围是()．A．B．C．D．E．