Part Five
Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.
That the plates are moving is not beyond dispute. Africa and South America, for example, are moving away from earth other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years.
The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops seed fissures（cracks）; in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability（inconstancy）.
17. The author believes that _____ .
A）the motion of the plates corresponds to that of the earth's interior
B）the geological theory about drifting plates has been proved to be true
C）the hot spots and the plates move slowly in opposite directions
D）the movement of hot spots proves the continents are moving apart
18. That Africa and South America were once joined can be deduced from the fact that _____ .
A）the two continents are still moving in opposite directions
B）they have been found to share certain geological features
C）the African plates has been stable for 30 million years
D）over 100 hot spots are scattered all around the globe
19. The hot spot theory may prove useful in explaining _____ .
A）the structure of the African plates B）the revival of dead volcanoes
C）the mobility of the continents D）the formation of new oceans
20. The passage is mainly about _____ .
A）the features of volcanic activities
B）the importance of the theory about drifting plates
C）the significance of hot spots in geophysical studies
D）the process of the formation of volcanoes
Unit 5 （1998）
Part 5重點(diǎn)詞匯：
1. interior （內(nèi)部的；內(nèi)部）←inter+ior，inter“在里面”，-ior后綴, n.
2. milestone （里程碑）←mile+stone。The invention of the wheel was a milestone in the history of the world.發(fā)明輪子是世界歷的重大事件。
3. reminder （n.暗示）←remind提醒+er。
4. construct （v.建設(shè)，構(gòu)造）即con+struct，con-“一起”，struct詞根“建造”；同義同根詞：structure（v.n.構(gòu)造）←struct+ure后綴。Taking to pieces is the trade of those who cannot construct.拆卸是那些不會(huì)建造的人的行為。
5. readily（容易地；樂(lè)意地）即ready的副詞形式，已經(jīng)準(zhǔn)備好的事情做起來(lái)當(dāng)然是“容易地”，于是做事的人當(dāng)然是非常“樂(lè)意地”。Nothing is so easy as to deceive one's self; for what we wish, that we readily believe.再?zèng)]有比欺騙自己更容易的事了，因?yàn)閷?duì)于希望的事，我們總是樂(lè)于相信。
6. opposite（對(duì)立的；對(duì)立面）即op+pos+ite，op-“反”（ob-在p前變形為op-），pos詞根“放”，-ite后綴，“反過(guò)來(lái)放”→對(duì)立的。
7. instrument（工具，儀器，樂(lè)器）即instru（ct）+ment，instruct指導(dǎo)，-ment后綴，“能幫人們做事的東西”→儀器。
8. significance? （意義；重要性）即signify（y變形為i）表示+cance名詞后綴，“表示出來(lái)的東西”→意義。形容詞形式為significant，
9. confine（v.限制）即con+fine，con-“一起”，fine詞根“界限”，于是“全部有界限”→限制。
10. reference（涉及；參考）←refer參考+ence。We live in reference to past experience and not to future events, however inevitable.我們參照過(guò)去的經(jīng)驗(yàn)而非未來(lái)的事件生活，不管那些事件如何必然發(fā)生。
11. propel （v.推動(dòng)，驅(qū)使）即pro+pel，pro-向前，pel詞根“推”。同根詞：compel（v.強(qiáng)迫）←com+pel；repel（v.擊退；抵制）←re（=back）+pel。
12. fissure （v.裂開(kāi)n.裂隙）看作f+is+sure，“裂開(kāi)”的東西上面有“縫”（f）是（is）肯定（sure）的。
13. formation （構(gòu)成）←form構(gòu)成+ation名詞后綴。The self is not something ready-made, but something in continuous formation through choice of action.自我并非現(xiàn)成之物，而是通過(guò)行為的選擇不斷形成的。
14. mutability（易變性）即mut+ability，mut詞根“交換”，-ability名詞后綴表性質(zhì)，“具有交換的性質(zhì)”→易變性。參commute，2000年P(guān)assage 4。mutability of human affairs 人世滄桑。
難句解析：
① Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate.
這是一個(gè)由兩個(gè)分句組成的并列句，中間由分號(hào)隔開(kāi)。前一個(gè)分句的第一個(gè)部分是一個(gè)形容詞性的短語(yǔ)，修飾的是這個(gè)句子的主語(yǔ)they，在plates的后面有一個(gè)that引導(dǎo)的定語(yǔ)從句，that所替代的plates在這個(gè)從句里作主語(yǔ)；第二個(gè)分句用on the contrary開(kāi)始，表示與前面的情況形成對(duì)比，這個(gè)句子較簡(jiǎn)單，注意這里them指的是前文所說(shuō)的hot spots。
注意兩個(gè)分句的對(duì)比關(guān)系，弄清哪個(gè)特征是they（hot spots）所具有的。
② The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined.
這個(gè)單句的主語(yǔ)是the complementary coastlines and certain geological features，后面帶了一個(gè)定語(yǔ)從句，從句中that充當(dāng)?shù)氖侵髡Z(yǔ)；表語(yǔ)名詞reminders跟了一個(gè)of加上where引導(dǎo)的名詞性表示地點(diǎn)從句的短語(yǔ)。where從句中用的是過(guò)去時(shí)，表示的是過(guò)去存在的結(jié)合狀態(tài)。
找出句子的主語(yǔ)、謂語(yǔ)（are）和表語(yǔ)（reminders），再看主語(yǔ)和表語(yǔ)的修飾成分。并注意reminders的意思是“值得注意的地方，具有提醒作用的地方”。
③ The relative motion of the plates carrying these continents has been constructed in detail, but the motion of the plates with respect to another cannot readily be translated into motion with respect to the earth's interior.
在這個(gè)用but連接的兩個(gè)并列分句中，前一個(gè)分句主語(yǔ)的限定成分the plates帶了一個(gè)現(xiàn)在分詞短語(yǔ)，起修飾作用；后一個(gè)分句中注意謂語(yǔ)be translated into意為“被解釋為”，這里的another指的是another plates。介詞whit respect to出現(xiàn)了兩次，意思是“相對(duì)于……”。
對(duì)介詞的理解是這個(gè)句子的關(guān)鍵，注意motion這個(gè)詞在本句中指的是相對(duì)運(yùn)動(dòng)。
④ It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it.
這個(gè)簡(jiǎn)單句的主語(yǔ)it是個(gè)形式主語(yǔ)，真正的主語(yǔ)是后面to引導(dǎo)的不定式短語(yǔ)。這個(gè)短語(yǔ)中，determine后面跟的是whether... or whether...引導(dǎo)的選擇關(guān)系的從句。注意后面whether從句中有兩個(gè)分句，用and連接，其中the other指的是the other continent。
找出該句真正的主語(yǔ)（不定式形式），注意兩個(gè)whether從句的選擇關(guān)系，以及后一個(gè)從句中兩個(gè)小句所描述的相對(duì)關(guān)系。
⑤ As the dome grows, it develops deep fissures（cracks）; in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean.
這個(gè)句子是由四個(gè)小分句組成，前兩個(gè)分句是一個(gè)主從復(fù)合句，其中it指的是the dome；分號(hào)后面的句子有一個(gè)狀語(yǔ)短語(yǔ)in at least a few cases，逗號(hào)后面是so that引導(dǎo)的表示結(jié)果的從句。
在理解這個(gè)句子時(shí)，是能按時(shí)間的先后排列地質(zhì)變化的過(guò)程。
試題解析：
17. 【正確答案】 [B]
意為：地質(zhì)學(xué)上的板塊漂移說(shuō)證明是正確的。第二段第一句指出，對(duì)于板塊漂移說(shuō)目前已不存異議（beyond dispute）。例如，非洲和南美洲正在漂離，新物質(zhì)不斷注入二者之間的海底裂痕。
A意為：板塊的移動(dòng)與地球內(nèi)部的移動(dòng)是相對(duì)應(yīng)的。第一段指出，地球有100多個(gè)地質(zhì)學(xué)家稱之為熱點(diǎn)的互不相鄰的（isolated）火山活躍區(qū)。與地球上多數(shù)火山不同的是：它們并非都處在構(gòu)成地球表面的巨大漂游板塊的連接處，相反，它們多深埋在板塊之下（lie deep in the interior of a plate）。這些熱點(diǎn)移動(dòng)緩慢，有時(shí)，當(dāng)板塊從它們上面移動(dòng)過(guò)去時(shí)，就會(huì)留下死火山痕跡（trails of dead volcanoes）。熱點(diǎn)及其火山痕跡標(biāo)志著板塊漂移而過(guò)?？梢?jiàn)，二者的移動(dòng)并沒(méi)有相應(yīng)處。C意為：熱點(diǎn)和板塊緩慢作反方向移動(dòng)。根據(jù)第一段，二者的移動(dòng)并沒(méi)有相應(yīng)處。參閱上文題解。D意為；熱點(diǎn)的移動(dòng)證明：大陸板塊正在漂離。根據(jù)第一段最后一句，熱點(diǎn)及其火山痕跡證明板塊是移動(dòng)的。
18. 【正確答案】 [B]
意為：它們有某些共同的地質(zhì)特征。第二段指出，對(duì)于板塊漂移說(shuō)目前已不存異議。例如，非洲和南美洲正在漂離，新物質(zhì)不斷注入二者之間的海底裂痕；雖然有大洋（大西洋）相隔，二者的海岸線（形狀）是互補(bǔ)的（complementary），共有某些地質(zhì)特征，說(shuō)明它們?cè)?jīng)是聯(lián)在一起的。
A意為：這兩個(gè)大陸還在向相反方向移動(dòng)。根據(jù)第二段最后一句，通過(guò)對(duì)熱點(diǎn)區(qū)域的研究發(fā)現(xiàn)，非洲板塊似乎是靜止的（stationary），至少3000萬(wàn)年未移動(dòng)了。C意為：非洲板塊至少3000萬(wàn)年未移動(dòng)了。這也許是事實(shí)，但不是非洲和南美洲曾經(jīng)是一個(gè)板塊的證據(jù)。D意為：地球有100多個(gè)熱點(diǎn)。這也許是事實(shí)，但這也不是非洲和南美洲曾經(jīng)是一個(gè)板塊的證據(jù)。
19. 【正確答案】 [D]
意為：新的海洋的形成。最后一段指出，熱點(diǎn)說(shuō)的意義不限于提供了一個(gè)參照點(diǎn)，它看來(lái)對(duì)推動(dòng)板塊移動(dòng)的地質(zhì)物理學(xué)過(guò)程也提供了解釋。當(dāng)板塊處于熱點(diǎn)之上時(shí)，底層物質(zhì)會(huì)將板塊頂起，形成（develop）巨大的弧線（a broad dome），弧線變高時(shí)，板塊出現(xiàn)深深的裂痕。當(dāng)有些地方裂痕迸裂后，就形成新的海洋。
A意為：非洲板塊的結(jié)構(gòu)。B意為；死火山的復(fù)活。C意為：大陸板塊的移動(dòng)性。熱點(diǎn)只能說(shuō)明板塊是移動(dòng)的，但板塊為什么是漂移的，本文卻并沒(méi)有解釋。
20. 【正確答案】 [C]
意為：地質(zhì)物理學(xué)中熱點(diǎn)說(shuō)的意義。本文提到了這種學(xué)說(shuō)的幾方面的意義。見(jiàn)上文題解。
A意為：火山活動(dòng)的特點(diǎn)。B意為：板塊漂移說(shuō)的重要性。D意為：火山的形成過(guò)程。
全文翻譯：
地球上散落分布著100多個(gè)互不相連的小火山活動(dòng)區(qū)，被地質(zhì)學(xué)家稱為熱點(diǎn)。和世界上大多數(shù)火山不同的是，它們并不總是在構(gòu)成地球表面的巨大漂流板塊之間的邊界上出現(xiàn)；相反，許多熱點(diǎn)處于板塊較深的內(nèi)部。大多數(shù)熱點(diǎn)移動(dòng)非常緩慢，有時(shí)，板塊滑過(guò)這些熱點(diǎn)便留下了死火山的痕跡。熱點(diǎn)及其火山痕跡是板塊移動(dòng)的標(biāo)志。
板塊漂移這一理論現(xiàn)在是毋庸置疑的。例如，以非洲和南美洲為例，由于有新的物質(zhì)注入二者之間的海底，兩大洲距離越來(lái)越遠(yuǎn)。但互相吻合的海岸線和某些似乎跨越海洋的地質(zhì)特征會(huì)使人想到這兩個(gè)大陸曾經(jīng)是連在一起的。攜帶這些大陸的板塊的相對(duì)運(yùn)動(dòng)已經(jīng)能夠被詳細(xì)地闡述出來(lái)，但一個(gè)板塊相對(duì)另一板塊的運(yùn)動(dòng)還不能輕易地解釋為它們相對(duì)于地球內(nèi)部的運(yùn)動(dòng)。人們不能確定兩個(gè)大陸是在朝相反的方向運(yùn)動(dòng)，還是一個(gè)大陸停止不動(dòng)而另一個(gè)從它身邊漂移開(kāi)去。位于地球更深層的熱點(diǎn)提供了解決該問(wèn)題的測(cè)量?jī)x器。從熱點(diǎn)地區(qū)的人口情況分析來(lái)看，非洲板塊似乎是固定的，在過(guò)去3000萬(wàn)年里也沒(méi)有移動(dòng)過(guò)。
熱點(diǎn)的重要性不僅限于它們作為參照體系的作用。現(xiàn)在看來(lái)，它們還對(duì)推動(dòng)板塊在地球表面漂移這一地球物理過(guò)程有重要影響。當(dāng)大陸板塊漂移到熱點(diǎn)上方，來(lái)自地球深層的物質(zhì)便形成了巨大的圓頂狀隆起物。隨著這個(gè)圓頂?shù)脑鲩L(zhǎng)，板塊出現(xiàn)深深的裂縫。至少有幾次，大陸可能會(huì)沿著其中的一些裂縫完全裂開(kāi)了，因此這個(gè)熱點(diǎn)就引發(fā)了一個(gè)新的海洋的形成。這樣，正像早期的理論解釋了大陸的移動(dòng)性一樣，熱點(diǎn)理論或許能解釋大陸板塊的不穩(wěn)定性。
Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.
That the plates are moving is not beyond dispute. Africa and South America, for example, are moving away from earth other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years.
The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops seed fissures（cracks）; in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability（inconstancy）.
17. The author believes that _____ .
A）the motion of the plates corresponds to that of the earth's interior
B）the geological theory about drifting plates has been proved to be true
C）the hot spots and the plates move slowly in opposite directions
D）the movement of hot spots proves the continents are moving apart
18. That Africa and South America were once joined can be deduced from the fact that _____ .
A）the two continents are still moving in opposite directions
B）they have been found to share certain geological features
C）the African plates has been stable for 30 million years
D）over 100 hot spots are scattered all around the globe
19. The hot spot theory may prove useful in explaining _____ .
A）the structure of the African plates B）the revival of dead volcanoes
C）the mobility of the continents D）the formation of new oceans
20. The passage is mainly about _____ .
A）the features of volcanic activities
B）the importance of the theory about drifting plates
C）the significance of hot spots in geophysical studies
D）the process of the formation of volcanoes
Unit 5 （1998）
Part 5重點(diǎn)詞匯：
1. interior （內(nèi)部的；內(nèi)部）←inter+ior，inter“在里面”，-ior后綴, n.
2. milestone （里程碑）←mile+stone。The invention of the wheel was a milestone in the history of the world.發(fā)明輪子是世界歷的重大事件。
3. reminder （n.暗示）←remind提醒+er。
4. construct （v.建設(shè)，構(gòu)造）即con+struct，con-“一起”，struct詞根“建造”；同義同根詞：structure（v.n.構(gòu)造）←struct+ure后綴。Taking to pieces is the trade of those who cannot construct.拆卸是那些不會(huì)建造的人的行為。
5. readily（容易地；樂(lè)意地）即ready的副詞形式，已經(jīng)準(zhǔn)備好的事情做起來(lái)當(dāng)然是“容易地”，于是做事的人當(dāng)然是非常“樂(lè)意地”。Nothing is so easy as to deceive one's self; for what we wish, that we readily believe.再?zèng)]有比欺騙自己更容易的事了，因?yàn)閷?duì)于希望的事，我們總是樂(lè)于相信。
6. opposite（對(duì)立的；對(duì)立面）即op+pos+ite，op-“反”（ob-在p前變形為op-），pos詞根“放”，-ite后綴，“反過(guò)來(lái)放”→對(duì)立的。
7. instrument（工具，儀器，樂(lè)器）即instru（ct）+ment，instruct指導(dǎo)，-ment后綴，“能幫人們做事的東西”→儀器。
8. significance? （意義；重要性）即signify（y變形為i）表示+cance名詞后綴，“表示出來(lái)的東西”→意義。形容詞形式為significant，
9. confine（v.限制）即con+fine，con-“一起”，fine詞根“界限”，于是“全部有界限”→限制。
10. reference（涉及；參考）←refer參考+ence。We live in reference to past experience and not to future events, however inevitable.我們參照過(guò)去的經(jīng)驗(yàn)而非未來(lái)的事件生活，不管那些事件如何必然發(fā)生。
11. propel （v.推動(dòng)，驅(qū)使）即pro+pel，pro-向前，pel詞根“推”。同根詞：compel（v.強(qiáng)迫）←com+pel；repel（v.擊退；抵制）←re（=back）+pel。
12. fissure （v.裂開(kāi)n.裂隙）看作f+is+sure，“裂開(kāi)”的東西上面有“縫”（f）是（is）肯定（sure）的。
13. formation （構(gòu)成）←form構(gòu)成+ation名詞后綴。The self is not something ready-made, but something in continuous formation through choice of action.自我并非現(xiàn)成之物，而是通過(guò)行為的選擇不斷形成的。
14. mutability（易變性）即mut+ability，mut詞根“交換”，-ability名詞后綴表性質(zhì)，“具有交換的性質(zhì)”→易變性。參commute，2000年P(guān)assage 4。mutability of human affairs 人世滄桑。
難句解析：
① Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate.
這是一個(gè)由兩個(gè)分句組成的并列句，中間由分號(hào)隔開(kāi)。前一個(gè)分句的第一個(gè)部分是一個(gè)形容詞性的短語(yǔ)，修飾的是這個(gè)句子的主語(yǔ)they，在plates的后面有一個(gè)that引導(dǎo)的定語(yǔ)從句，that所替代的plates在這個(gè)從句里作主語(yǔ)；第二個(gè)分句用on the contrary開(kāi)始，表示與前面的情況形成對(duì)比，這個(gè)句子較簡(jiǎn)單，注意這里them指的是前文所說(shuō)的hot spots。
注意兩個(gè)分句的對(duì)比關(guān)系，弄清哪個(gè)特征是they（hot spots）所具有的。
② The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined.
這個(gè)單句的主語(yǔ)是the complementary coastlines and certain geological features，后面帶了一個(gè)定語(yǔ)從句，從句中that充當(dāng)?shù)氖侵髡Z(yǔ)；表語(yǔ)名詞reminders跟了一個(gè)of加上where引導(dǎo)的名詞性表示地點(diǎn)從句的短語(yǔ)。where從句中用的是過(guò)去時(shí)，表示的是過(guò)去存在的結(jié)合狀態(tài)。
找出句子的主語(yǔ)、謂語(yǔ)（are）和表語(yǔ)（reminders），再看主語(yǔ)和表語(yǔ)的修飾成分。并注意reminders的意思是“值得注意的地方，具有提醒作用的地方”。
③ The relative motion of the plates carrying these continents has been constructed in detail, but the motion of the plates with respect to another cannot readily be translated into motion with respect to the earth's interior.
在這個(gè)用but連接的兩個(gè)并列分句中，前一個(gè)分句主語(yǔ)的限定成分the plates帶了一個(gè)現(xiàn)在分詞短語(yǔ)，起修飾作用；后一個(gè)分句中注意謂語(yǔ)be translated into意為“被解釋為”，這里的another指的是another plates。介詞whit respect to出現(xiàn)了兩次，意思是“相對(duì)于……”。
對(duì)介詞的理解是這個(gè)句子的關(guān)鍵，注意motion這個(gè)詞在本句中指的是相對(duì)運(yùn)動(dòng)。
④ It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it.
這個(gè)簡(jiǎn)單句的主語(yǔ)it是個(gè)形式主語(yǔ)，真正的主語(yǔ)是后面to引導(dǎo)的不定式短語(yǔ)。這個(gè)短語(yǔ)中，determine后面跟的是whether... or whether...引導(dǎo)的選擇關(guān)系的從句。注意后面whether從句中有兩個(gè)分句，用and連接，其中the other指的是the other continent。
找出該句真正的主語(yǔ)（不定式形式），注意兩個(gè)whether從句的選擇關(guān)系，以及后一個(gè)從句中兩個(gè)小句所描述的相對(duì)關(guān)系。
⑤ As the dome grows, it develops deep fissures（cracks）; in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean.
這個(gè)句子是由四個(gè)小分句組成，前兩個(gè)分句是一個(gè)主從復(fù)合句，其中it指的是the dome；分號(hào)后面的句子有一個(gè)狀語(yǔ)短語(yǔ)in at least a few cases，逗號(hào)后面是so that引導(dǎo)的表示結(jié)果的從句。
在理解這個(gè)句子時(shí)，是能按時(shí)間的先后排列地質(zhì)變化的過(guò)程。
試題解析：
17. 【正確答案】 [B]
意為：地質(zhì)學(xué)上的板塊漂移說(shuō)證明是正確的。第二段第一句指出，對(duì)于板塊漂移說(shuō)目前已不存異議（beyond dispute）。例如，非洲和南美洲正在漂離，新物質(zhì)不斷注入二者之間的海底裂痕。
A意為：板塊的移動(dòng)與地球內(nèi)部的移動(dòng)是相對(duì)應(yīng)的。第一段指出，地球有100多個(gè)地質(zhì)學(xué)家稱之為熱點(diǎn)的互不相鄰的（isolated）火山活躍區(qū)。與地球上多數(shù)火山不同的是：它們并非都處在構(gòu)成地球表面的巨大漂游板塊的連接處，相反，它們多深埋在板塊之下（lie deep in the interior of a plate）。這些熱點(diǎn)移動(dòng)緩慢，有時(shí)，當(dāng)板塊從它們上面移動(dòng)過(guò)去時(shí)，就會(huì)留下死火山痕跡（trails of dead volcanoes）。熱點(diǎn)及其火山痕跡標(biāo)志著板塊漂移而過(guò)?？梢?jiàn)，二者的移動(dòng)并沒(méi)有相應(yīng)處。C意為：熱點(diǎn)和板塊緩慢作反方向移動(dòng)。根據(jù)第一段，二者的移動(dòng)并沒(méi)有相應(yīng)處。參閱上文題解。D意為；熱點(diǎn)的移動(dòng)證明：大陸板塊正在漂離。根據(jù)第一段最后一句，熱點(diǎn)及其火山痕跡證明板塊是移動(dòng)的。
18. 【正確答案】 [B]
意為：它們有某些共同的地質(zhì)特征。第二段指出，對(duì)于板塊漂移說(shuō)目前已不存異議。例如，非洲和南美洲正在漂離，新物質(zhì)不斷注入二者之間的海底裂痕；雖然有大洋（大西洋）相隔，二者的海岸線（形狀）是互補(bǔ)的（complementary），共有某些地質(zhì)特征，說(shuō)明它們?cè)?jīng)是聯(lián)在一起的。
A意為：這兩個(gè)大陸還在向相反方向移動(dòng)。根據(jù)第二段最后一句，通過(guò)對(duì)熱點(diǎn)區(qū)域的研究發(fā)現(xiàn)，非洲板塊似乎是靜止的（stationary），至少3000萬(wàn)年未移動(dòng)了。C意為：非洲板塊至少3000萬(wàn)年未移動(dòng)了。這也許是事實(shí)，但不是非洲和南美洲曾經(jīng)是一個(gè)板塊的證據(jù)。D意為：地球有100多個(gè)熱點(diǎn)。這也許是事實(shí)，但這也不是非洲和南美洲曾經(jīng)是一個(gè)板塊的證據(jù)。
19. 【正確答案】 [D]
意為：新的海洋的形成。最后一段指出，熱點(diǎn)說(shuō)的意義不限于提供了一個(gè)參照點(diǎn)，它看來(lái)對(duì)推動(dòng)板塊移動(dòng)的地質(zhì)物理學(xué)過(guò)程也提供了解釋。當(dāng)板塊處于熱點(diǎn)之上時(shí)，底層物質(zhì)會(huì)將板塊頂起，形成（develop）巨大的弧線（a broad dome），弧線變高時(shí)，板塊出現(xiàn)深深的裂痕。當(dāng)有些地方裂痕迸裂后，就形成新的海洋。
A意為：非洲板塊的結(jié)構(gòu)。B意為；死火山的復(fù)活。C意為：大陸板塊的移動(dòng)性。熱點(diǎn)只能說(shuō)明板塊是移動(dòng)的，但板塊為什么是漂移的，本文卻并沒(méi)有解釋。
20. 【正確答案】 [C]
意為：地質(zhì)物理學(xué)中熱點(diǎn)說(shuō)的意義。本文提到了這種學(xué)說(shuō)的幾方面的意義。見(jiàn)上文題解。
A意為：火山活動(dòng)的特點(diǎn)。B意為：板塊漂移說(shuō)的重要性。D意為：火山的形成過(guò)程。
全文翻譯：
地球上散落分布著100多個(gè)互不相連的小火山活動(dòng)區(qū)，被地質(zhì)學(xué)家稱為熱點(diǎn)。和世界上大多數(shù)火山不同的是，它們并不總是在構(gòu)成地球表面的巨大漂流板塊之間的邊界上出現(xiàn)；相反，許多熱點(diǎn)處于板塊較深的內(nèi)部。大多數(shù)熱點(diǎn)移動(dòng)非常緩慢，有時(shí)，板塊滑過(guò)這些熱點(diǎn)便留下了死火山的痕跡。熱點(diǎn)及其火山痕跡是板塊移動(dòng)的標(biāo)志。
板塊漂移這一理論現(xiàn)在是毋庸置疑的。例如，以非洲和南美洲為例，由于有新的物質(zhì)注入二者之間的海底，兩大洲距離越來(lái)越遠(yuǎn)。但互相吻合的海岸線和某些似乎跨越海洋的地質(zhì)特征會(huì)使人想到這兩個(gè)大陸曾經(jīng)是連在一起的。攜帶這些大陸的板塊的相對(duì)運(yùn)動(dòng)已經(jīng)能夠被詳細(xì)地闡述出來(lái)，但一個(gè)板塊相對(duì)另一板塊的運(yùn)動(dòng)還不能輕易地解釋為它們相對(duì)于地球內(nèi)部的運(yùn)動(dòng)。人們不能確定兩個(gè)大陸是在朝相反的方向運(yùn)動(dòng)，還是一個(gè)大陸停止不動(dòng)而另一個(gè)從它身邊漂移開(kāi)去。位于地球更深層的熱點(diǎn)提供了解決該問(wèn)題的測(cè)量?jī)x器。從熱點(diǎn)地區(qū)的人口情況分析來(lái)看，非洲板塊似乎是固定的，在過(guò)去3000萬(wàn)年里也沒(méi)有移動(dòng)過(guò)。
熱點(diǎn)的重要性不僅限于它們作為參照體系的作用。現(xiàn)在看來(lái)，它們還對(duì)推動(dòng)板塊在地球表面漂移這一地球物理過(guò)程有重要影響。當(dāng)大陸板塊漂移到熱點(diǎn)上方，來(lái)自地球深層的物質(zhì)便形成了巨大的圓頂狀隆起物。隨著這個(gè)圓頂?shù)脑鲩L(zhǎng)，板塊出現(xiàn)深深的裂縫。至少有幾次，大陸可能會(huì)沿著其中的一些裂縫完全裂開(kāi)了，因此這個(gè)熱點(diǎn)就引發(fā)了一個(gè)新的海洋的形成。這樣，正像早期的理論解釋了大陸的移動(dòng)性一樣，熱點(diǎn)理論或許能解釋大陸板塊的不穩(wěn)定性。