数据流程图(DFD)是用于数据库设计中( )阶段的工具。A．概念设计 B．逻辑设计

计算机中十六位浮点数的表示格式为图1.4

某机器码为1010001010000000。
若阶码为移码且尾数为反码，则其真值为 (60) ；
若阶码为移码且尾数为原码，则其真值为 (61) ；
若阶码为补码且尾数为反码，则其真值为 (62) ；
若阶码为补码且尾数为原码，则其真值为 (63) ，将其规格化后的机器码为 (64) 。

A．0.00000001012

B．2010

C．1.2510

D．20.96937510

1945年英国议会通过了大英银行国有化法案，建立了英国史上第一个国家银行；1946年政府将800家公司收归国有；1947年政府在电力、航空、电讯、航运等企业部门推行国有化。这表明[ ]

A．英国开始走上了计划经济的道路

B．英国经济出现了严重的滞胀

C．英国政府加强了对经济的干预

D．社会主义在西方建立起来

一般而言，帕金森病多是因人类大脑中产生多巴胺的细胞死亡而发病的。华盛顿大学的研究人员用一些基因改造过的双翅目昆虫果蝇来做实验，这些果蝇在迈入老年时期时，多巴胺细胞会逐渐死亡。科学家惊奇地发现，当他们将烟草、咖啡榨成汁，喂给这些果蝇以后，果蝇们的多巴胺细胞又增多了，而且这些果蝇又变得生龙活虎起来。因此，研究者指出，有烟瘾和嗜好咖啡的人，得帕金森病的几率更低。
如果以下各项为真，不能质疑上述推测的是( )。

A．人类与果蝇大脑产生多巴胺细胞的机制存在差异
B．实验的4个小组当中，其中1组得出了相反结果
C．人类大脑中的多巴胺细胞过量分泌容易导致暴力犯罪
D．多数双翅目昆虫在获得新食物种类后均会产生多巴胺细胞分泌增多现象

In opposing the 1970 Clean Air Act, the United States automobile industry argued that meeting the act’s standards for automobile emissions was neither economically feasible nor environmentally necessary. However, the catalytic converter, invented in 1967, enable automakers to meet the 1970 standards efficiently. Currently, automakers are lobbying against the government’s attempt to pass legislation that would tighten restrictions on automobile emissions. The automakers contend that these new restrictions would be overly expensive and unnecessary to efforts to curb air pollution. Clearly, the automobile industry’s position should not be heeded.
Which one of the following, if true, lends the most support to the automakers’ current position

A．The more stringent the legislation restricting emissions becomes, the more difficult it becomes for automakers to provide the required technology economically.

B．Emissions-restriction technology can often be engineered so as to avoid reducing the efficiency with which an automobile uses fuel.

C．Not every new piece of legislation restricting emissions requires new automotive technology in order for automakers to comply with it.

D．The more automobiles there are on the road, the more stringent emission restrictions must be to prevent increased overall air pollution.

E．(E) Unless forced to do so by the government, automakers rarely make changes in automotive technology that is not related to profitability.