日本的季风气候具有（ ） A．大陆性特征 B．海洋性特征 C．高山性特征 D．临

某井水中含有钙离子、镁离子和碳酸氢根离子等，该井水属于[ ]

A.纯净物

B.氧化物

C.化合物

D.混合物

材料一：进入新世纪，在新技术革命的作用下，生产力的国际化与专业化协作的程度越来越高，跨国公司加速发展。据统计，全球外汇市场每天交易额已达到1.7万亿美元。

材料二：据世界银行统计的数字显示，如果按人均GDP水平把全世界的国家分成5等份，人均GDP水平属于最高的20%的国家与人均GDP水平属于最低的20%的国家之间的差距，1987年是57倍，1997年扩大为92倍。尤其令人忧虑的是，发展中国家与发达国家在高新技术领域的差距更为悬殊，“数字鸿沟”在不断加大。“新经济”至今只是一种“富国现象”，而大多数发展中国家仍然处于“信息贫困”之中。

（1）材料一、二各反映了什么经济现象？请对此作简要分析。

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（2）结合我国实际，说明我们应如何面对上述材料所反映的问题。

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下列关于 PowerDesigner 的叙述中，正确的是______。

A．只能在概念层上建立和维护数据模型

B．只能在物理（逻辑）层上建立和维护数据模型

C．既能在概念层上也能在物理层上建立和维护数据模型

D．既不能在概念层上也不能在物理层上建立和维护数据模型

门静脉血流量约占肝血流量的80%～89%。()

阅读理解。

    On October 12, 1987, some Chinese scientists were working at the computers to look for

information they needed. Suddenly they saw a lot of very bright spots (点) crossing the

computers' screens. At the same time the computers were working much slower. To find out

what was happening they stopped their work to check some parts of the computers. To their

horror (恐惧), they found out that most of their stored information was got rid of (除掉)

by computer viruses! Obviously all these computers had been infected (感染) by computer

viruses.

    It is said that the computer viruses were made by a group of young man fond of playing

tricks. They all had excellent education. They created the viruses just to show their

intelligence. (才智) These kinds of computer viruses are named Jerusalem (耶路撒冷)

Viruses. These viruses can stay in computers for a long time. When the time comes they

will attack the computers by lowering the function (功能), damaging their normal programs

or even getting rid of all the information.

    We now come to know that Jerusalem Viruses often attack computers on Fridays and that

they are spreading (传播) to a list of computers. Among the countries that suffering

computer viruses are Britain, Australia, Switzerland and the U.S. But till now, how to

get rid of the terrible remains a problem.

1. The group of young men created the viruses to ______. [ ]

A. damage the computers

B. test their ability

C. tell the world that they were intelligent

D. play a trick on operators of the computers

2. According to the passage, computer viruses seem to ______.[ ]

A. have been in nature for years

B. exist (存在) in any computers

C. be difficult to get rid of at present

D. be able to be got rid of in the near future

3. The most serious damage caused by the viruses is that ______. [ ]

A. the computer's functions are lowered

B. the normal programs are damaged

C. all the information stored in the computers is gone

D. the computers infected by the viruses can no longer be used

4. According to the passage, which of the following is true? [ ]

A. Four countries found their computers were infected by viruses.

B. The viruses will come to a new computer after staying in the old one for some time.

C. Scientists are trying to find a way to get rid of the viruses.

D. The Jerusalem Viruses are a great harm to human health.