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. The study published in the journal Nature indicates that （）
第1题：
25．In studying ，we must always ask "whys" in order to ________．
A． understand the book well
B． get some questions to ask our teachers
C． do with the new words
D． write down the questions
第2题：
DOM is a platform-and language-(21)API that allows programs and scripts to dynamically access and update the content, structure and style. of WWW documents (currently ,definitions for HTML and XML documents are part of the specification). The document can be further processed and the results of that processing can be incorporated back into the presented(22). DOM is a(23)-based AP1 to documents, which requires the whole document to be represented in(24)while processing it. A simpler alternative to DOM is the event-based SAX, which can be used to process very large(25)documents that do not fit info the memory available for processing.
A．specific
B．neutral
C．contained
D．related
第3题：
在 X.25 网络中， （21） 是网络层协议。
（21）A. LAP-B
B. X.21
C. X.25PLP
D. MHS
第4题：
第5题：
第6题：
Originally introduced by Netscape Communications,(21)are a general mechanism which HTTP Server side applications, such as CGI(22), can use to both store and retrieve information on the HTTP(23)side of the connection. Basically, Cookies can be used to compensate for the(24)nature of HTTP. The addition of a simple, persistent, client-side state significantly extends the capabilities of WWW-based(25).
A．Browsers
B．Cookies
C．Connections
D．Scripts
第7题：
对一组数据(84，47，25，15，21)排序，数据的排列次序在排序过程中的变化为(1)84 47 25 15 21(2)15 47 25 84 21(3)15 21 25 84 47(4)15 21 25 47 84，则采用的排序是(36)。
A．选择
B．冒泡
C．快速
D．插入
第8题：
The reason why lesson six skips the puzzle questions is that they are associated with the expertise based on the content of a particular subject which is likely irrelevant to a layman.()
第9题：
第10题：