专家解题：2012年职称英语考试理工类B级概括大意

考题类型：概括大意与完成句子

              Learn aboutNoble Gases(惰性气体)

1    Have you ever ridden on aballoon? Many tourist spots offer balloon rides in order for people to see thebeauty of a place from above. A balloon contains a noble gas called helium（氦）.Formerly, balloons contained hydrogen but hydrogen is very flammable anddangerous when uncontrolled. Therefore, people shifted to helium, which issafer. Helium is safe because it has the properties of the noble gases.

2    People once believed thatnoble gases couldn’t chemically react at all. For this reason, they were called inertgases（惰性气体）. They were also listed under Group 0 in the old periodic tablebecause scientists believed that the gases have zero valence（价） electronsin their outer hell. This was later proven to be untrue when some noble gascompounds were discovered.

3   The gases are elements,which share similar properties. These properties include being monoatomic,colorless, odorless, being able to conduct electricity, and having low chemicalreactivity. Noble gases include Helium, Neon, Argon, Krypton, Xenon and Radon.These are all found in Group 18, in the rightmost column of the periodic table.If you look at the periodic table, you will notice that these elements are theonly ones, which do not have a charge. Helium has the lowest molecular（分子的） weightwhile Radon is the heaviest.

4   Remember that chemicalreactions occur because atoms have valence electrons, which are electrons intheir outer shell. When the outer shell is “unfilled” or the required number ofelectrons is not yet complete, the atom is more reactive. Noble gases have afull outer shell, meaning that they have complete electrons in their outershell. This complete number varies. For instance, the outer shell of Helium has2 valence electrons while the outer shell of Xenon has 8 electrons. Nowadays,there remains to be a few noble gases because of the low chemical reactivity ofthese said gases.

5    Because of theirproperties, noble gases have many important applications. They are widely usedin medicine and industries. For instance, Liquid Helium is used forsuperconducting magnets（磁体）. These magnets are very important in physics and medicine. When adoctor suspects that a person’s brain has been damaged, he might request forMagnetic Resonance Imaging (MRI). MRI allows the doctor to “see” the brain,without operating on the patient.

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23. Paragraph 2 ______

A. What are the applications of noble gases?

B. How were noble gases discovered?

C. What are noble gases?

D. What causes the low chemical reactivity of noble gases?

E. How were noble gases understood in the past?

F. What is the periodic table?

　专家解题：

第一步：划出各个选项的中心词。A：应用applications；B：怎么发现的？How……discovered？C：noble gases是什么？ D：引起了低化学反应cause the low chemical reactivity；E：过去被理解understoodin the past；F：周期表periodic table。

第二步：找出第二段的中心句。本段的中心句就在段落的第一句：People once believed that noble gases……，意思是：人们曾经认为noblegases……。

第三步：对比选项，确定答案。和“曾经认为”相关的选项就应该是选项E的How were noble gases understood in the past?意思是：以前人们是怎么理解noblegases的？选项E的内容符合该段的主要意思，所以本题的正确答案为选项E。

24. Paragraph 3 ______

A. What are the applications of noble gases?

B. How were noble gases discovered?

C. What are noble gases?

D. What causes the low chemical reactivity of noble gases?

E. How were noble gases understood in the past?

F. What is the periodic table?

　专家解题：

第一步：找出第三段的中心句。本段的中心句就在段落的第一句：The gases are elements, which share similar properties. 意思是：The gases是elements, ……。

第二步：对比选项，确定答案。和中心句相关的选项就应该是选项C的What are noble gases?意思是： noble gases是什么？选项C的内容符合该段的主要意思，所以本题的正确答案为选项C。这道题涉及到了我们概括大意中很典型的一个题目，也就是下定义的表示方法：what is/are……。

25. Paragraph 4 ______

A. What are the applications of noble gases?

B. How were noble gases discovered?

C. What are noble gases?

D. What causes the low chemical reactivity of noble gases?

E. How were noble gases understood in the past?

F. What is the periodic table?

　专家解题：

第一步：找出第四段的中心句。本段的中心句就在段落的最后一句：Nowadays, there remains to be a few noble gases because of theinherent low chemical reactivity of these said gases.

第二步：对比选项，确定答案。和中心句相关的选项就应该是选项D的What cause the low chemical reactivity of noble gases? 只有该选项中出现了中心句的关键词the low chemical reactivity。所以本题的正确答案为选项D。

26. Paragraph 5 ______

A. What are the applications of noble gases?

B. How were noble gases discovered?

C. What are noble gases?

D. What causes the low chemical reactivity of noble gases?

E. How were noble gases understood in the past?

F. What is the periodic table?

　专家解题：

第一步：找出第五段的中心句。本段的中心句就在段落的第一句：Because of their properties, noble gases have many importantapplications.

第二步：对比选项，确定答案。和中心句相关的选项就应该是

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