巧用虛擬語(yǔ)氣解答GRE閱讀題
巧用虛擬語(yǔ)氣解答GRE閱讀題,我們來(lái)看看吧，下面小編就和大家分享，來(lái)欣賞一下吧。
巧用虛擬語(yǔ)氣解答GRE閱讀題
(1) 對(duì)虛擬語(yǔ)氣的敏感性
若在文章中看到虛擬語(yǔ)氣，考慮直接取非反義理解，迅速把握作者態(tài)度。如下面這句話：
例一：Perhaps, some scientists thought, migrants determine their geographic position on Earth by celestial navigation, almost as human navigators use stars and planets, but this would demand of the animals a fantastic map sense. (選自N0.6題第一套section 1短文章)
這句話看似很長(zhǎng)，翻譯成為中文的意思是：“有些科學(xué)家認(rèn)為，就像人類采用恒星和行星來(lái)定位一樣，候鳥或許也是采用天體的導(dǎo)航才得以確定它們所處的地理位置，但這要求這類動(dòng)物具有令人難以置信的地圖感?！敝形淖x過(guò)去都讓人頭疼。其實(shí)我們用虛擬語(yǔ)氣取非的思想來(lái)處理，其要表達(dá)的意思就很簡(jiǎn)單，對(duì)前半句話取非，說(shuō)白了就是前半句話是行不通的，也就是“migrants cannot determine their geographic position on Earth by celestial navigation?！笨梢灾雷髡邔?duì)這種解釋持負(fù)評(píng)價(jià)。2016年GRE考試場(chǎng)次大比較高分考生親授報(bào)名時(shí)間選擇技巧
我們?cè)賮?lái)看個(gè)例子：
例二：According to natural selection theory, a worker would enhance her fitness—or ability to propagate her genes—by hatching her own eggs in addition to or in place of the queen’s。(選自國(guó)內(nèi)題1993年10月考題section 5短文章)
這句話也是虛擬語(yǔ)氣，我們直接取反理解，作者想要表達(dá)的就是“a worker will not enhance her …”
運(yùn)用這種取非的思想我們可以迅速的把握作者的態(tài)度，以及作者想要表達(dá)的真實(shí)意思。就不用先翻譯成繞口的中文，再拼命的思索其中的含義，可以有效地為考試爭(zhēng)取時(shí)間。
(2) 如何運(yùn)用虛擬語(yǔ)氣
在題干中看到虛擬語(yǔ)氣，大多需要用到取非思想，與之相對(duì)應(yīng)的一種題型是GRE閱讀題中常見(jiàn)的一種，叫做“改進(jìn)型取非題”?？蠢又?，先簡(jiǎn)單解釋下什么是“改進(jìn)型取非題”。很簡(jiǎn)單，如果題干問(wèn)“如果一個(gè)對(duì)象怎樣會(huì)更好”則是改進(jìn)型取非題，來(lái)看具體的例子：
例：It can be inferred from the passage that the “first theories”of grazer control mentioned in line 3 would have been more convincing if researchers had been able to(選自NO.6第二套section 1長(zhǎng)文章)，這是一個(gè)典型的改進(jìn)型取非題題干，問(wèn)的是第三行第一個(gè)理論怎樣會(huì)更好。
邏輯思路：既然是改進(jìn)，原文肯定說(shuō)到了它的不好之處或者有unless的句子，我們把造成不好的原因取非，就是所要的答案了。
按照此思路定位原文三行，看到后面有這樣一句話“A low number of algal cells in the presence of a high number of grazers suggested, but did not prove, that the grazers had removed most of the algae?！弊⒁饪床迦胝Z(yǔ)部分的“but did not prove”，這個(gè)就是缺點(diǎn)，取非就是“prove”再看五個(gè)選項(xiàng)：
(A) observe high phytoplankton numbers under natural lake conditions
(B) discover negative correlations between algae and zooplankton numbers from their field research
(C) understand the central importance of environmental factors in controlling the growth rates of phytoplankton
(D) make verifiable correlations of cause and effect between zooplankton and phytoplankton numbers
(E) invent laboratory techniques that would have allowed them to bypass their field research concerning grazer control
一眼掃過(guò)去就只有一個(gè)選項(xiàng)在講證明，就是D中的verifiable。所以答案選D。很快解完此題。
(3) 虛擬語(yǔ)氣的作用
取非的思路除了可以在虛擬語(yǔ)氣中使用，還可以在另一種邏輯關(guān)系中使用，就是強(qiáng)對(duì)比的關(guān)系，也就是GRE閱讀題中另一種?？碱}型“強(qiáng)對(duì)比互取非題”，其主要特點(diǎn)是：原文中有強(qiáng)對(duì)比的雙方，題干只問(wèn)及其中一方，答案是對(duì)另一方敘述的取非;或者題干和原文存在強(qiáng)對(duì)比要素，如典型的時(shí)間要素，答案也是對(duì)原文的敘述取非。
來(lái)看個(gè)簡(jiǎn)單的例子，
例：The author suggests that, before the early 1950’s, most historians who studied preindustrial Europe did which of the following(選自NO.6第三套section 4 長(zhǎng)文章)
思路：在題干中看到了1950’s，第一反應(yīng)就是要回原文定位，發(fā)現(xiàn)原文只講到了“in the early 1950’s”并沒(méi)有“before”，這顯然就是時(shí)間上一個(gè)取非的關(guān)系，我們把in the early 1950’s干的事情取個(gè)非，就是之前干的事情。答案就很好選了，在此不舉出來(lái)了。
gre 閱讀虛擬語(yǔ)氣中這個(gè)思路很好理解，比如說(shuō)“我1995年第一次去北京?！焙茱@然，1995年以前我就沒(méi)有去過(guò)北京。這就是時(shí)間狀語(yǔ)的取非。其它的強(qiáng)對(duì)比關(guān)系(如處于相對(duì)低于空間的事物通常其特點(diǎn)呈強(qiáng)對(duì)比;新事物、新觀點(diǎn)和舊事物、傳統(tǒng)觀點(diǎn)呈強(qiáng)對(duì)比;用最高級(jí)、唯一性限定的事物和其余所有同類事物的特征呈強(qiáng)對(duì)比等)，相信考生可以一眼看出。
GRE考試閱讀理解模擬題及答案解析
P1
Traditional research has confronted only Mexican and United States interpretations of Mexican-American culture.
Now we must also examine the culture as we Mexican Americans have experienced it, passing from a sovereign people to compatriots with newly arriving settlers to, finally, a conquered people — a charter minority on our own land.
When the Spanish first came to Mexico, they inter-married with and absorbed the culture of the indigenous Indians.
This policy of colonization through acculturation was continued when Mexico acquired Texas in the early 1800‘s and brought the indigenous Indians into Mexican life and government.
In the 1820‘s, United States citizens migrated to Texas, attracted by land suitable for cotton.
As their numbers became more substantial, their policy of acquiring land by subduing native populations began to dominate.
The two ideologies clashed repeatedly, culminating in a military conflict that led to victory for the United States.
Thus, suddenly deprived of our parent culture, we had to evolve uniquely Mexican-American modes of thought and action in order to survive. (168 words)
1. The author‘s purpose in writing this passage is primarily to
(A) suggest the motives behind Mexican and United States intervention in Texas
(B) document certain early objectives of Mexican-American society
(C) provide a historical perspective for a new analysis of Mexican-American culture
(D) appeal to both Mexican and United States scholars to give greater consideration to economic interpretations of history
(E) bring to light previously overlooked research on Mexican Americans
2. The author most probably uses the phrase “charter minority” (lines 6-7) to reinforce the idea that Mexican Americans
(A) are a native rather than an immigrant group in the United States
(B) played an active political role when Texas first became part of the United States
(C) recognized very early in the nineteenth century the need for official confirmation of their rights of citizenship
(D) have been misunderstood by scholars trying to interpret their culture
(E) identify more closely with their Indian heritage than with their Spanish heritage
3. Which of the following statements most clearly contradicts the information in this passage?
(A) In the early 1800‘s, the Spanish committed more resources to settling California than to developing Texas.
(B) While Texas was under Mexican control, the population of Texas quadrupled, in spite of the fact that Mexico discouraged immigration from the United States.
(C) By the time Mexico acquired Texas, many Indians had already married people of Spanish heritage.
(D) Many Mexicans living in Texas returned to Mexico after Texas was annexed by the United States.
(E) Most Indians living in Texas resisted Spanish acculturation and were either killed or enslaved.
P2
The determination of the sources of copper ore used in the manufacture of copper and bronze artifacts of Bronze Age civilizations would add greatly to our knowledge of cultural contacts and trade in that era.
Researchers have analyzed artifacts and ores for their concentrations of elements, but for a variety of reasons, these studies have generally failed to provide evidence of the sources of the copper used in the objects.
Elemental composition can vary within the same copper-ore lode, usually because of varying admixtures of other elements, especially iron, lead, zinc, and arsenic.
And high concentrations of cobalt or zinc, noticed in some artifacts, appear in a variety of copper-ore sources.
Moreover, the processing of ores introduced poorly controlled changes in the concentrations of minor and trace elements in the resulting metal.
Some elements evaporate during smelting and roasting; different temperatures and processes produce different degrees of loss.
Finally, flux, which is sometimes added during smelting to remove waste material from the ore, could add quantities of elements to the final product.
An elemental property that is unchanged through these chemical processes is the isotopic composition of each metallic element in the ore.
Isotopic composition, the percentages of the different isotopes of an element in a given sample of the element, is therefore particularly suitable as an indicator of the sources of the ore.
Of course, for this purpose it is necessary to find an element whose isotopic composition is more or less constant throughout a given ore body, but varies from one copper ore body to another or, at least, from one geographic region to another.
The ideal choice, when isotopic composition is used to investigate the source of copper ore, would seem to be copper itself.
It has been shown that small but measurable variations occur naturally in the isotopic composition of copper.
However, the variations are large enough only in rare ores; between samples of the common ore minerals of copper, isotopic variations greater than the measurement error have not been found.
An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes.
The isotopic composition of lead often varies from one source of common copper ore to another, with variations exceeding the measurement error; and preliminary studies indicate virtually uniform isotopic composition of the lead from a single copper-ore source.
While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore.
Lead isotope studies may thus prove useful for interpreting the archaeological record of the Bronze Age. (473 words)
4. The author first mentions the addition of flux during smelting in the last sentence in the last paragraph in order to
(A) give a reason for the failure of elemental composition studies to determine ore sources
(B) illustrate differences between various Bronze Age civilizations
(C) show the need for using high smelting temperatures
(D) illustrate the uniformity of lead isotope composition
(E) explain the success of copper isotope composition analysis
For the following question, consider each of the choices separately and select all that apply
5. According to the passage, possible sources of the lead found in a copper or bronze artifact include which of the following?
□A The copper ore used to manufacture the artifact
□B Flux added during processing of the copper ore
□C Other metal added during processing of the copper ore
6. Select the sentence in the passage that the author rejects copper as the “ideal choice” .
7. It can be inferred from the passage that the use of flux in processing copper ore can alter the lead isotope composition of the resulting metal EXCEPT when
(A) there is a smaller concentration of lead in the flux than in the copper ore
(B) the concentration of lead in the flux is equivalent to that of the lead in the ore
(C) some of the lead in the flux evaporates during processing
(D) any lead in the flux has the same isotopic composition as the lead in the ore
(E) other metals are added during processing
1
Traditional research has confronted only Mexican and United States interpretations of Mexican-American culture.
傳統(tǒng)的對(duì)墨西哥裔美國(guó)人文化的研究，一直以來(lái)只注意墨西哥和美國(guó)視角的解讀。
2
Now we must also examine the culture as we Mexican Americans have experienced it, passing from a sovereign people to compatriots with newly arriving settlers to, finally, a conquered people — a charter minority on our own land.
現(xiàn)在我們也必須從墨西哥裔美國(guó)人的歷史經(jīng)驗(yàn)出發(fā)考察這種文化，從自治到成為一國(guó)的國(guó)民，從新登陸的開拓者到被征服者——這片土地上的少數(shù)族群。
3
When the Spanish first came to Mexico, they inter-married with and absorbed the culture of the indigenous Indians.
西班牙人剛到墨西哥就與當(dāng)?shù)厝送ɑ?，并吸收了?dāng)?shù)氐挠〉诎参幕?/p>
4
This policy of colonization through acculturation was continued when Mexico acquired Texas in the early 1800‘s and brought the indigenous Indians into Mexican life and government.
這種文化融合的政策，在1800年代早期墨西哥擴(kuò)展到德州時(shí)仍在發(fā)揮作用，(德州)當(dāng)?shù)氐挠〉诎踩艘簿偷靡赃M(jìn)入墨西哥人的生活與治理。
5
In the 1820‘s, United States citizens migrated to Texas, attracted by land suitable for cotton.
1820年代，美國(guó)人遷徙到德州，發(fā)現(xiàn)這片土地很適合種棉花。
6
As their numbers became more substantial, their policy of acquiring land by subduing native populations began to dominate.
美國(guó)人越來(lái)越多，他們的政策轉(zhuǎn)而以強(qiáng)征當(dāng)?shù)厝说耐恋貫橹鳌?/p>
7
The two ideologies clashed repeatedly, culminating in a military conflict that led to victory for the United States.
兩種意識(shí)形態(tài)不斷沖突，最終爆發(fā)了武裝沖突，以美國(guó)的勝利告終。
8
Thus, suddenly deprived of our parent culture, we had to evolve uniquely Mexican-American modes of thought and action in order to survive. (168 words)
因此，當(dāng)?shù)厝耸チ嗽械奈幕?，不得不發(fā)展出一種墨西哥裔美國(guó)人的思維和行為方式，以圖生存。
1. The author‘s purpose in writing this passage is primarily to
(A) suggest the motives behind Mexican and United States intervention in Texas
(B) document certain early objectives of Mexican-American society
(C) provide a historical perspective for a new analysis of Mexican-American culture
(D) appeal to both Mexican and United States scholars to give greater consideration to economic interpretations of history
(E) bring to light previously overlooked research on Mexican Americans
選C
A 暗示了墨西哥和美國(guó)干涉德州事物背后的動(dòng)機(jī)，搞笑
B 記錄了墨美社會(huì)特定的早期目標(biāo)，瞎聊
C 提供了一種新的分析墨美文化的史學(xué)觀點(diǎn)，正確項(xiàng)，句1，2
D 呼吁墨西哥和美國(guó)的學(xué)者更重視從經(jīng)濟(jì)角度解釋歷史，瞎聊
E 揭示了一直被忽略的關(guān)于墨美人的研究，瞎聊
2. The author most probably uses the phrase “charter minority” (lines 6-7) to reinforce the idea that Mexican Americans
(A) are a native rather than an immigrant group in the United States
(B) played an active political role when Texas first became part of the United States
(C) recognized very early in the nineteenth century the need for official confirmation of their rights of citizenship
(D) have been misunderstood by scholars trying to interpret their culture
(E) identify more closely with their Indian heritage than with their Spanish heritage
選A
挺精致的一題。
charter 我們?cè)诤茉缫郧暗囊粋€(gè)填空題里講過(guò) “黃熱病肆虐北美，以至于費(fèi)城 lost its charter ”，charter 是指英國(guó)頒發(fā)給海外殖民者，建立城市的特許狀，其中規(guī)定了殖民城市所擁有的武裝、稅收等權(quán)力。
結(jié)合本段內(nèi)容，墨西哥人是西班牙人加南美土著，他們來(lái)到德州，接納了德州當(dāng)?shù)氐耐林@些人相處是比較融洽的，他們通婚，文化上也融合。
但這群倒霉蛋后來(lái)碰上來(lái)種棉花的美國(guó)人，美國(guó)人就不那么友好了，通過(guò)武力強(qiáng)搶當(dāng)?shù)厝说耐恋亍Ｄ敲匆坏┙⒘?Texas ，美國(guó)人的 charter 是不太可能保障前者的權(quán)益的，他們?cè)谶@個(gè)新建立的政權(quán)中，自然就成了少數(shù)派 minority 。
A 墨美人是當(dāng)?shù)厝?，而不是外?lái)族群
B 墨美人在墨西哥時(shí)期的德州是統(tǒng)治階層的一部分，美國(guó)人來(lái)了就不是了
C 十九世紀(jì)早期，是個(gè)非常模糊的范圍，1800年其實(shí)是承認(rèn)當(dāng)?shù)厝藱?quán)力的，1820年代美國(guó)人來(lái)了，情況開始轉(zhuǎn)變，所以這個(gè)描述不清晰，不選
D 不能看出其他學(xué)者 misunderstood 了，也可能只是忽略了
E 看不出與西班牙更近還是印第安人更近，更類似于聯(lián)合政府，西班牙換成美國(guó)就對(duì)了
3. Which of the following statements most clearly contradicts the information in this passage?
(A) In the early 1800‘s, the Spanish committed more resources to settling California than to developing Texas.
(B) While Texas was under Mexican control, the population of Texas quadrupled, in spite of the fact that Mexico discouraged immigration from the United States.
(C) By the time Mexico acquired Texas, many Indians had already married people of Spanish heritage.
(D) Many Mexicans living in Texas returned to Mexico after Texas was annexed by the United States.
(E) Most Indians living in Texas resisted Spanish acculturation and were either killed or enslaved.
選E
A 不一定，文中沒(méi)說(shuō)加州的事，無(wú)法判斷
B quadurpled 四倍于，不能判斷
C 墨西哥統(tǒng)治德州以前，當(dāng)?shù)厝司团c西班牙裔通婚，不能判斷
D 美國(guó)吞并德州，很多墨西哥人逃回墨西哥，不能判斷
E 多數(shù)印第安人反抗西班牙人的文化融合政策，被殺被奴役，這個(gè)正好說(shuō)反了，是美國(guó)人動(dòng)粗的，墨西哥統(tǒng)治德州時(shí)，當(dāng)?shù)厝说拇霾诲e(cuò)，還能參與城市管理，見(jiàn)句4
P2
1
The determination of the sources of copper ore used in the manufacture of copper and bronze artifacts of Bronze Age civilizations would add greatly to our knowledge of cultural contacts and trade in that era.
了解青銅時(shí)代的文明如何確定用來(lái)制造銅和青銅制品的銅礦石，會(huì)極大地幫助我們了解那個(gè)時(shí)代文明間的交流和貿(mào)易。
2
Researchers have analyzed artifacts and ores for their concentrations of elements, but for a variety of reasons, these studies have generally failed to provide evidence of the sources of the copper used in the objects.
研究者們已經(jīng)分析過(guò)這些制品和礦石中各元素的含量，但由于種.種原因，這些研究大多不能為銅的來(lái)源提供證據(jù)。
3
Elemental composition can vary within the same copper-ore lode, usually because of varying admixtures of other elements, especially iron, lead, zinc, and arsenic.
一處礦脈中的元素構(gòu)成可能有差異，通常是因?yàn)榛烊肓瞬煌康钠渌?，特別是鐵，鉛，鋅，砷。
4
And high concentrations of cobalt or zinc, noticed in some artifacts, appear in a variety of copper-ore sources.
而在某些制品中可以觀察到，某些銅礦石來(lái)源中鈷或鋅的含量高。
5
Moreover, the processing of ores introduced poorly controlled changes in the concentrations of minor and trace elements in the resulting metal.
而且，礦石的生產(chǎn)工藝顯示，煉制出的金屬中的微量元素含量的變化無(wú)法有效控制。
6
Some elements evaporate during smelting and roasting; different temperatures and processes produce different degrees of loss.
有些元素在熔煉和鍛造過(guò)程中蒸發(fā);不同的溫度和工藝過(guò)程造成不同程度的損耗。
7
Finally, flux, which is sometimes added during smelting to remove waste material from the ore, could add quantities of elements to the final product.
最后，熔劑，加入到熔煉過(guò)程中用來(lái)從礦石中去除廢料的一種物質(zhì)，也會(huì)在成品中混入一定量的其他元素。
8
An elemental property that is unchanged through these chemical processes is the isotopic composition of each metallic element in the ore.
經(jīng)過(guò)這些化學(xué)工藝，一個(gè)不變的性質(zhì)是礦石中每種金屬元素的同位素構(gòu)成比例。
9
Isotopic composition, the percentages of the different isotopes of an element in a given sample of the element, is therefore particularly suitable as an indicator of the sources of the ore.
同位素構(gòu)成，是某元素的一份樣品中各種同位素所占的百分比，所以它特別適合作為鑒定礦石來(lái)源的指標(biāo)。
10
Of course, for this purpose it is necessary to find an element whose isotopic composition is more or less constant throughout a given ore body, but varies from one copper ore body to another or, at least, from one geographic region to another.
當(dāng)然，為了完成測(cè)定有必要找到這樣一種元素，它在一塊礦石中的同位素構(gòu)成比例或多或少是穩(wěn)定的，但在不同礦石，或不同地域出產(chǎn)的礦石中它的比例互相區(qū)別。
11
The ideal choice, when isotopic composition is used to investigate the source of copper ore, would seem to be copper itself.
當(dāng)我們用同位素構(gòu)成比例來(lái)調(diào)查銅礦石來(lái)源，理想的選擇，似乎就是銅本身。
12
It has been shown that small but measurable variations occur naturally in the isotopic composition of copper.
我們已經(jīng)知道銅的同位素構(gòu)成在自然情況下會(huì)發(fā)生小但可測(cè)量的變化。
13
However, the variations are large enough only in rare ores; between samples of the common ore minerals of copper, isotopic variations greater than the measurement error have not been found.
然而，這種改變只有在稀有礦石中才足夠大(可測(cè)量);普通銅礦物樣本的同位素差異，一般都小于測(cè)量誤差。
14
An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes.
另一種選擇是鉛，在多數(shù)青銅時(shí)代的銅以及青銅制品中都含有鉛，數(shù)量大體與銅礦石中的鉛相當(dāng)，也可能有部分來(lái)自熔劑。
15
The isotopic composition of lead often varies from one source of common copper ore to another, with variations exceeding the measurement error; and preliminary studies indicate virtually uniform isotopic composition of the lead from a single copper-ore source.
同類型來(lái)源的不同普通銅礦石中，鉛的同位素比例通常不同，這種差異超過(guò)了測(cè)量誤差的范圍;且初步的研究顯示，單一銅礦樣本中的同位素比例實(shí)際上是一致的。
16
While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore.
盡管有些制品中的鉛可能來(lái)自于熔劑或熔煉銅礦過(guò)程中加入的其他金屬，青銅時(shí)代工藝中這些被加入的鉛，經(jīng)常與銅礦中的鉛有著相同的同位素比例。
17
Lead isotope studies may thus prove useful for interpreting the archaeological record of the Bronze Age. (473 words)
所以，鉛的同位素研究可能幫助我們解釋青銅時(shí)代的某些考古記錄。
4. The author first mentions the addition of flux during smelting in the last sentencein the last paragraph in order to(在文章第14句)
(A) give a reason for the failure of elemental composition studies to determine ore sources
(B) illustrate differences between various Bronze Age civilizations
(C) show the need for using high smelting temperatures
(D) illustrate the uniformity of lead isotope composition
(E) explain the success of copper isotope composition analysis
選A
我們先回頭看看句14，
“An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes. ”
如果鉛完全來(lái)自于礦石，那么是有追蹤效果的。如果鉛來(lái)自外加的物質(zhì)，萬(wàn)一加入的鉛的同位素構(gòu)成，跟礦石中的鉛的同位素構(gòu)成數(shù)值差異很大，就可能干擾檢測(cè)的結(jié)果，所以這里提出鉛可能來(lái)自熔劑，是一種科學(xué)的保守，也就是 A 項(xiàng)描述。
For the following question, consider each of the choices separately and select all that apply
5. According to the passage, possible sources of the lead found in a copper or bronze artifact include which of the following?
□A The copper ore used to manufacture the artifact
□B Flux added during processing of the copper ore
□C Other metal added during processing of the copper ore
選ABC
句 14 告訴我們銅礦石中都含有鉛，句16告訴我們?nèi)蹮掃^(guò)程中加入熔劑和其他金屬，也可能帶入了鉛，所以選 ABC 。
6. Select the sentence in the passage that the author rejects copper as the “ideal choice” .
句13
“However, the variations are large enough only in rare ores; between samples of the common ore minerals of copper, isotopic variations greater than the measurement error have not been found. ”
我們要測(cè)量某種差異，測(cè)量過(guò)程中也一定會(huì)發(fā)生誤差，只有當(dāng)這種差異在相當(dāng)程度上超過(guò)誤差的規(guī)模時(shí)，我們才能采信這種結(jié)果。
比如我要回憶我跟我小學(xué)同桌的學(xué)習(xí)程度的對(duì)比，回憶的對(duì)象是期末考試分?jǐn)?shù)，回憶可能存在幾分的偏差。
假設(shè)我同桌學(xué)習(xí)特棒總是95左右，那么算上偏差她可能90-100分，而我一般都是75，算上偏差也不會(huì)到80以上，則這種對(duì)比是有明確結(jié)果的。
如果我們都是80分左右，則我的回憶完全不能比較我們的程度差異，也許我們?cè)摀Q一種方式，比如回母校查閱當(dāng)年考試成績(jī)的記錄。
7. It can be inferred from the passage that the use of flux in processing copper ore can alter the lead isotope composition of the resulting metal EXCEPT when
(A) there is a smaller concentration of lead in the flux than in the copper ore
(B) the concentration of lead in the flux is equivalent to that of the lead in the ore
(C) some of the lead in the flux evaporates during processing
(D) any lead in the flux has the same isotopic composition as the lead in the ore
(E) other metals are added during processing
選D
非常好的邏輯題。
前面第 4 題，我們知道，要確定銅，我們用了鉛，但是鉛可能有外來(lái)一些干擾，題目問(wèn)我們哪種情況下可以排除這種干擾，注意 EXCEPT 。
如果加入的鉛在同位素構(gòu)成比例上，和礦石中原有的鉛相同，加多少也就無(wú)所謂，因?yàn)槲乙獪y(cè)的是同位素的衰減程度。
就好像我要研究80歲左右的老頭，如果60年前混入我們研究范圍的男青年也都是20歲，那么現(xiàn)在他們也80歲了，不影響我們調(diào)查80歲老頭的結(jié)果。
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