计算机病毒只会破坏磁盘上的数据和文件。

[单选题]Questions 21 to 25 are based on the following passage. Lead deposits, which accumulated in soil and snow during the 1960’s and 70’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly. A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining. In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate (区分) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States. In a study published in the journal Ambio, scientists found that lead levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline. Many scientists had believed that the lead would stay in soil and snow for a longer period. The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected. Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute. Lead accumulation worldwide decreased significantly after the use of unleaded gas in the US （）

[单选题]ATM/CDM密码须设立几位数（）

[单选题]关于细菌L型.错误的说法是（　　）。

[问答题]×年×月×日18时15分，某炼油厂油品分厂罐区发生爆炸，引起310号油罐燃烧，造成2人死亡，直接经济损失约39万元。事故当日13时许，某炼油厂油品分厂半成品车间工人黄某在当班期间，发现310号油罐油面高度已达14．21m，接近警戒高度14．30m，黄某马上向该厂总调度进行了报告，并向总调度请示310号油罐汽油调和量。根据总调度的指示，黄某进入罐区将油切换至304号油罐。13时30分许，黄某在给310号油罐作汽油调和流程准备时，本应打开310号罐D400出口阀门，却误开了311号油罐D400出口阀门。15时许，黄某开启11A号泵欲对310号油罐进行自循环调和，由于错开了311号D400出口阀门，实际上此时310号油罐不是在自循环，而是将311号罐中的汽油抽入310号油罐。15时40分，仪表工陈某某从计算机显示屏上发现310号油罐油面不断上升，随后计算机开始“高位报警”，陈某当即让黄某到罐区去核实一下310号罐的油面高度，黄某却误认为是计算机不准确，没去核实也未采取其他措施。16时，在交班时违反规定，没有在油罐现场进行交接班，也未核实油罐流程。17时50分，310号油罐的汽油开始外冒，部分汽油挥发，在空气中形成爆炸性混合气体。18时15分，某单位职工吕某驾驶手扶拖拉机路过罐区11号路时，排气管排出的火星遇空气中的爆炸混合气体发生起火爆炸，导致吕某当场死亡，另一工人被严重烧伤抢救无效死亡。310号油罐"-3即燃烧，持续17h后被扑灭。 1.如果310号油罐和311号油罐相距400m，且都是直径l5m的圆柱形罐体，其最高油面高度是l4．3m，试判断该储存单元是否构成重大危险源。汽油在储存区的临界量是20t，汽油的密度是750kg／m3。 2.试分析该罐区具有哪些危险因素，并指出防止危险因素演变为事故的控制措施有哪些。3.试分析该事故发生的直接原因和间接原因。

[单选题]下列关于认知治疗相关观点错误的是（）。

[单选题]冷库温度应保持在（）

[判断题]纳税人将不同税率的应税消费品组成成套消费品销售的，如果分别核算不同税率应税消费品的销售额、销售数量的，应按不同税率分别计算不同消费品应纳的消费税。（）

[问答题]玻璃表面装饰方法有哪些？

[多选题]以下是调车作业通知单应有内容的是（）。

[问答题]为什么要对关系代数表达式进行优化？

[判断题]计算机病毒只会破坏磁盘上的数据和文件。

[判断题]计算机病毒只会破坏磁盘上的数据和文件。

[判断题]计算机病毒只会破坏软盘上的数据和文件。

[判断题]计算机病毒只会破坏软件，不能损坏硬件。

[单选题]计算机病毒主要是造成（）的破坏。

[单选题]计算机病毒主要是造成（）破坏。

[单选题]计算机病毒不能破坏（）

[单选题]计算机病毒主要是造成（）的破坏。

[单选题]计算机病毒主要是造成（）破坏。

[单选题]计算机病毒不能破坏（）。