現在大傢在進行托福備考時 TPO 托福模考軟件相信是大傢用的最多的工具瞭，對於托福成績的提升是非常有幫助的。托福聽力可以說是整個托福考試當中比較重要的一個部分，如何利用現有資料 TPO 模考軟件來提升大傢的托福成績呢 ? 今天小編在這裡整理瞭 TPO8 托福聽力 Lecture4 文本 + 題目 + 答案解析來分享給大傢，希望對大傢托福聽力備考有幫助。
TPO8 托福聽力 Lecture4 原文文本
Narrator: Listen to part of a lecture in a Chemistry class. The professor has been discussing the periodical table of elements.
Pro: So, are there any questions?
Stu: Yes, um, Professor Harrison, you were saying that the periodic table is predictive. What exactly does that mean? I mean I understand how it organizes the elements, but where ’ s the prediction?
Pro: Ok, let ’ s look at our periodic table again. Ok, it groups elements into categories that share certain properties, right?
Stu: Uh-huh.
Pro: And it is arranged according to increasing atomic number, which is …
Stu: The number of protons in each atom of an element.
Pro: Right. Well, early versions of the periodic table had gaps, missing elements. Every time you had one more proton, you had another element. And then, oops, there ’ d be an atomic number, for which there was no known element. And the prediction was that an element with that atomic number existed somewhere, but it just hadn ’ t been found yet. And its location in the table would tell you what properties it should have. It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties.
Um, actually, that reminds me of a ... of a very good example of all these, element 43. See on the table, the symbols for elements 42 and 44. Well, in early versions of the table, there was no symbol for an element 43 protons because no element with 43 protons had been discovered yet. So the periodic table had a gap between elements 42 and 44.
And then in 1925, a team of chemists led by a scientist named Ida Tacke claimed that they had found element 43. They had been using a relatively new technology called X-ray spectroscopy, and they were using this to examine an ore sample. And they claimed that they ’ d found an element with 43 protons. And they named it Masurium.
Stu: Um, Professor Harrison, then, how come in my periodic table here, element 43 is Tc? That ’ s Technetium, right?
Pro: Ok, let me add that. Actually, um, that ’ s the point I ’ m coming to. Hardly anyone believed that Tacke ’ d discovered a new element. X-ray spectroscopy was a new method at that time. And they were never able to isolate enough Masurium to have a weighable sample to convince everyone of the discovery. So they were discredited. But then, 12 years later in 1937, a different team became the first to synthesize an element using a cyclotron. And that element had …
Stu: 43 protons?
Pro: That ’ s right, but they named it Technetium to emphasize that it was artificially created with technology. And people thought that synthesizing this element, making it artificially was the only way to get it. We still hadn ’ t found it occurring in nature. Now element 43, whether you call it Masurium or Technetium, is radioactive. Why does that matter? What is true of a radioactive element?
Stu: It decays, it turns into other elements. Oh, so does that explain why it was missing in the periodic table?
Pro: Exactly, because of its radioactive decay, element 43 doesn ’ t last very long. And therefore, if that ever had been present on Earth, it would have decayed ages ago. So the Masurium people were obviously wrong, and the Technetium people were right. Right? Well, that was then.
Now we know that element 43 does occur naturally.It can be naturally generated from Uranium atoms that have spontaneously split. And guess what, the ore sample the Masurium group was working with had plenty of Uranium in it, enough to split into measurable amounts of Masurium. So Tacke ’ s team might very well have found small amounts of Masurium in the ore samples. It ’ s just that once was generated from split Uranium, it decayed very quickly.
And you know here ’ s an incredible irony. Ida Tacke, the chemist led the Masurium team, well, she was the first to suggest that Uranium could break up into smaller pieces, but she didn ’ t know that that was the defense of her own discovery of element 43.
Stu: So is my version of the periodic table wrong? Should element 43 really be called Masurium?
Pro: Maybe, but you know it ’ s hard to tell for sure after all this time, if Ida Tacke ’ s group did discover element 43. They didn ’ t, um, publish enough detail on their methods or instruments for us to know for sure.
But I ’ d like to think element 43 was discovered twice. As Masurium, it was the first element discovered that occurs in nature only from spontaneous fission, and as Technetium, it was the first element discovered in a laboratory. And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it.
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TPO8 托福聽力 Lecture4 題目文本
Question 1 of 6
In the beginning of the lecture a student asks a question about the periodic table. How does the story of element 43 answer her question?
A. By providing an example of an element whose place in the periodic table was moved.
B. By providing an example of an element whose existence was predictable from the periodic table.
C. By providing an example of an element which scientists predicted was formed from uranium.
D. By providing an example of an element that can only be made artificially.
Question 2 of 6
What does the professor say about early versions of the periodic table?
A. Early versions listed two names for some elements.
B. Early versions had the incorrect atomic number for some elements.
C. Early versions were not as easy to use as modern version.
D. Early versions did not list an element for every atomic number.
Question 3 of 6
What fact inspired researchers to give the name "technetium" to element 43?
A. The element was radioactive.
B. The element was derived from uranium.
C. The element was created artificially.
D. The element was found using x-ray spectroscopy.
Question 4 of 6
What characteristic of element 43 might explain why the scientific community doubted the findings of Ida Tacke's team?
A. Element 43 has a very fast rate of decay.
B. lement 43 always contains small amount of other elements.
C. Element 43 cannot be created artificially.
D. Element 43's radioactivity makes it easy to isolate and measure.
Question 5 of 6
What does the professor believe about the claim that Ida Tacke's team made about element 43?
A. Scientists should have accepted the claim when it was first published.
B. There is not enough evidence to know if the team actually discovered element 43.
C. The team's unusual scientific methods were unreliable.
D. If the team's ore sample had contained element 43,the team would have been able to isolate a weighable amount.
Question 6 of 6
What does the professor imply about the chemist Ida Tacke when he says this?
A. She did not realize that the periodic table predicted the radioactivity of element 43.
B. She did not understand why her team's findings were dismissed by the scientific community.
C. Her theory about uranium would have explained the presence of element 43 in her team's ore sample.
D. Her theory about uranium would have explained the errors that created element 43 in a cyclotron.
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TPO8 托福聽力 Lecture4 答案解析
正確答案：B
題目解析：教授先說解釋瞭 element 的 predictable。又說 Um, actually, that reminds other, other very good example of all these, element 43. See on the table, the symbol for element 42 and 44.43 號元素是 predictable 的。
Question2 of 6
正確答案：D
題目解析：原文中明確提到元素周期表 had gaps, missing elements，因此可以推出答案 D
正確答案：C
題目解析：原文中的 artificially 呼應 C 選項，故答案為 C。
正確答案：A
題目解析：文中明確提到瞭 Ida 元素衰減的速度之快，和 A 選項呼應。
題目解析：They didn ’ t, um, publish enough detail 這個說法中可以看出教授對於 Tacke's team 對於元素 43 的說法還不是非常確定。
題目解析：從 irony, 和 the defense of her own discovery 可以推出答案 C。
以上就是小編為大傢整理瞭 TPO8 托福聽力 Lecture4 文本 + 題目 + 答案解析，大傢可以邊借助 TPO 模考軟件聽音頻看看自己哪些地方聽不懂，然後來看看原文，同時對練習托福聽力精聽也是很有幫助的。最後，小站教育編輯預祝大傢托福考試能取得理想的成績。
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