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Tunas, mackerels, and billfishes (marlins, sailfishes, and swordfish) swim continuously. Feeding,courtship, reproduction, and even "rest" are carried out while in constant motion. As a result,practically every aspect of the body form and function of these swimming "machines" isadapted to enhance their ability to swim.
Many of the adaptations of these fishes serve to reduce water resistance (drag). Interestinglyenough, several of these hydrodynamic adaptations resemble features designed to improve theaerodynamics of high-speed aircraft. Though human engineers are new to the game, tunasand their relatives evolved their "high-tech" designs long ago.
Tunas, mackerels, and billfishes have made streamlining into an art form. Their bodies aresleek and compact. The body shapes of tunas, in fact, are nearly ideal from an engineeringpoint of view. Most species lack scales over most of the body, making it smooth and eyes lie flush with the body and do not protrude at all. They are also covered with a slick,transparent lid that reduces drag. The fins are stiff, smooth, and narrow, qualities that alsohelp cut drag. When not in use, the fins are tucked into special grooves or depressions so thatthey lie flush with the body and do not break up its smooth contours. Airplanes retract theirlanding gear while in flight for the same reason.
Tunas, mackerels, and billfishes have even more sophisticated adaptations than these toimprove their hydrodynamics. The long bill of marlins, sailfishes, and swordfish probably helpsthem slip through the water. Many supersonic aircraft have a similar needle at the nose.
Most tunas and billfishes have a series of keels and finlets near the tail. Although most of theirscales have been lost, tunas and mackerels retain a patch of coarse scales near the headcalled the corselet. The keels, finlets, and corselet help direct the flow of water over the bodysurface in such as way as to reduce resistance (see the figure). Again, supersonic jets havesimilar features.
Because they are always swimming, tunas simply have to open their mouths and water is forcedin and over their gills. Accordingly, they have lost most of the muscles that other fishes use tosuck in water and push it past the gills. In fact, tunas must swim to breathe. They must alsokeep swimming to keep from sinking, since most have largely or completely lost the swimbladder, the gas-filled sac that helps most other fish remain buoyant.
One potential problem is that opening the mouth to breathe detracts from the streamlining ofthese fishes and tends to slow them down. Some species of tuna have specialized grooves intheir tongue. It is thought that these grooves help to channel water through the mouth andout the gill slits, thereby reducing water resistance.
There are adaptations that increase the amount of forward thrust as well as those that reducedrag. Again, these fishes are the envy of engineers. Their high, narrow tails with swept-backtips are almost perfectly adapted to provide propulsion with the least possible effort. Perhapsmost important of all to these and other fast swimmers is their ability to sense and make use ofswirls and eddies (circular currents) in the water. They can glide past eddies that would slowthem down and then gain extra thrust by "pushing off" the eddies. Scientists and engineers arebeginning to study this ability of fishes in the hope of designing more efficient propulsionsystems for ships.
The muscles of these fishes and the mechanism that maintains a warm body temperature arealso highly efficient. A bluefin tuna in water of 7°C (45°F) can maintain a core temperature ofover 25°C (77"F). This warm body temperature may help not only the muscles to work better,but also the brain and the eyes. The billfishes have gone one step further. They have evolvedspecial "heaters" of modified muscle tissue that warm the eyes and brain, maintaining peakperformance of these critical organs.
Paragraph 1: Tunas, mackerels, and billfishes (marlins, sailfishes, and swordfish) swimcontinuously. Feeding, courtship, reproduction, and even "rest" are carried out while inconstant motion. As a result, practically every aspect of the body form and function of theseswimming "machines" is adapted to enhance their ability to swim.
1. The word enhance in the passage is closest in meaning to
○Use
○Improve
○Counteract
○Balance
Paragraph 3: Tunas, mackerels, and billfishes have made streamlining into an art form. Theirbodies are sleek and compact. The body shapes of tunas, in fact, are nearly ideal from anengineering point of view. Most species lack scales over most of the body, making it smoothand slippery. The eyes lie flush with the body and do not protrude at all. They are also coveredwith a slick, transparent lid that reduces drag. The fins are stiff, smooth, and narrow,qualities that also help cut drag. When not in use, the fins are tucked into special grooves ordepressions so that they lie flush with the body and do not break up its smooth lanes retract their landing gear while in flight for the same reason.
2. The word they in the passage refers to
○Qualities
○Fins
○Grooves
○Depressions
3. Why does the author mention that Airplanes retract their landing gear while in flight?
○To show that air resistance and water resistance work differently from each other
○To argue that some fishes are better designed than airplanes are
○To provide evidence that airplane engine have studied the design of fish bodies
○To demonstrate a similarity in design between certain fishes and airplanes
Paragraph 4: Tunas, mackerels, and billfishes have even more sophisticated adaptations thanthese to improve their hydrodynamics. The long bill of marlins, sailfishes, and swordfishprobably helps them slip through the water. Many supersonic aircraft have a similar needle atthe nose.
4. The word sophisticated in the passage is closest in meaning to
○Complex
○Amazing
○Creative
○Practical
5. According to paragraph4, the long bills of marlins, sailfish, and swordfish probably help thesefishes by
○Increasing their ability to defend themselves
○Allowing them to change direction easily
○Increasing their ability to detect odors
○Reducing water resistance as they swim
Paragraph 6: Because they are always swimming, tunas simply have to open their mouths andwater is forced in and over their gills. Accordingly, they have lost most of the muscles thatother fishes use to suck in water and push it past the gills. In fact, tunas must swim tobreathe. They must also keep swimming to keep from sinking, since most have largely orcompletely lost the swim bladder, the gas-filled sac that helps most other fish remain buoyant.
6. According to the passage, which of the following is one of the reasons that tunas are inconstant motion?
○They lack a swim bladder.
○They need to suck in more water than other fishes do.
○They have large muscles for breathing.
○They cannot open their mouths unless they are in motion.
Paragraph 7: One potential problem is that opening the mouth to breathe detracts from thestreamlining of these fishes and tends to slow them down. Some species of tuna havespecialized grooves in their tongue. It is thought that these grooves help to channel waterthrough the mouth and out the gill slits, thereby reducing water resistance.
7. Which of the sentences below best expresses the essential information in the highlightedsentence in the passage?
Incorrect answer choices change the meaning in important ways or leave out essentialinformation,
○These fishes often have a problem opening their mouths while swimming.
○The streamlining of these fishes prevents them from slowing down.
○The streamlining of these fishes tends to slow down their breathing.
○Opening the mouth to breathe can reduce the speed of these fishes.
8. The word channel in the passage is closest in meaning to
○Reduce
○Remove
○Direct
○Provide
Paragraph 8: There are adaptations that increase the amount of forward thrust as well as thosethat reduce drag. Again, these fishes are the envy of engineers. Their high, narrow tails withswept-back tips are almost perfectly adapted to provide propulsion with the least possibleeffort. Perhaps most important of all to these and other fast swimmers is their ability to senseand make use of swirls and eddies (circular currents) in the water. They can glide past eddiesthat would slow them down and then gain extra thrust by "pushing off" the eddies. Scientistsand engineers are beginning to study this ability of fishes in the hope of designing moreefficient propulsion systems for ships.
9. According to the passage, one of the adaptations of fast-swimming fishes that might beused to improve the performance of ships is these fishes' ability to
○Swim directly through eddies
○Make efficient use of water currents
○Cover great distances without stopping
○Gain speed by forcing water past their gills
Paragraph 9: The muscles of these fishes and the mechanism that maintains a warm bodytemperature are also highly efficient. A bluefin tuna in water of 7°C (45°F) can maintain acore temperature of over 25°C (77°F). This warm body temperature may help not only themuscles to work better, but also the brain and the eyes. The billfishes have gone one stepfurther. They have evolved special "heaters" of modified muscle tissue that warm the eyes andbrain, maintaining peak performance of these critical organs.
10. According to paragraph 9, which of the following is true of bluefin tunas?
○Their eyes and brain are more efficient than those of any other fish.
○Their body temperature can change greatly depending on the water temperature.
○They can swim in waters that are much colder than their own bodies.
○They have special muscle tissue that warms their eyes and brain.
Again, supersonic jets have similar features.
Paragraph 6: ■Because they are always swimming, tunas simply have to open their mouths andwater is forced in and over their gills. ■Accordingly, they have lost most of the muscles thatother fishes use to suck in water and push it past the gills. ■In fact, tunas must swim tobreathe. ■They must also keep swimming to keep from sinking, since most have largely orcompletely lost the swim bladder, the gas-filled sac that helps most other fish remain buoyant.
11. Look at the four squares [■l that indicate where the following sentence can be added tothe passage.
Consequently, tunas do not need to suck in water.
Where would the sentence best fit?
12. Directions: Complete the table below by indicating which features of fishes are associated inthe passage with reducing water resistance and which are associated with increasing question is worth 3 points.
REDUCING WATER RESISTANCE INCREASING THRUST
●
●
● ●
●
Features of Fishes
1. The absence of scales from most of the body
2. The ability to take advantage of eddies
3. The ability to feed and reproduce while swimming
4. Eyes that do not protrude
5. Fins that are stiff, narrow, and smooth
6. The habit of swimming with the mouth open
7. A high, narrow tail with swept-back tips
參考答案
1. ○ 2
This is a Vocabulary question. The word being tested is enhance. It is highlighted in thepassage. The correct answer is choice 2, "improve." To enhance something means to "make itbetter." If something has been "improved," it has been made better.
2. ○2
This is a Reference question. The word being tested is they. It is highlighted in the ce 2, "fins," is the correct answer. This is a simple pronoun-referent item. The word theyrefers to something that lies flush with the body when not in use. This is true only of "fins."
3. ○ 4
This is a Rhetorical Purpose question. It asks why the author mentions that "Airplanes retracttheir landing gear while in flight." The phrase being tested is highlighted in the passage. Thecorrect answer is choice 4, "To demonstrate a similarity in design between certain fishes andairplanes." The paragraph in which the highlighted phrase appears describes how certain fishuse their fins. The highlighted phrase is used to provide a more familiar example (airplanes) ofthe principle involved to help the reader visualize how fins work. The paragraph does notdiscuss airplanes in any other context, so choices 2 and 3 are incorrect. Air and waterresistance are not mentioned in this paragraph, so choice 1 is incorrect.
4. ○ 1
This is a Vocabulary question. The word being tested is sophisticated. It is high lighted in thepassage. The correct answer is choice 1, "complex." If something is sophisticated, it is "notsimple," so it must be "complex."
5. ○ 4
This is a Factual Information question asking for specific information that can be found inparagraph 4. The correct answer is choice 4, "reducing water resistance as they swim." Theoverall theme of the passage is how certain fish swim so efficiently. Paragraphs 1 and 2make the general statement that "practically every aspect of the body form and function ofthese swimming 'machines' is adapted to enhance their ability to swim. Many of theadaptations of these fishes serve to reduce water resistance (drag)." Paragraph 4 explicitlystates (emphasis added) that "Tunas, mackerels, and billfishes have even more sophisticatedadaptations than these to improve their hydrodynamics. The long bill of marlins, sailfishes, andswordfish probably helps them slip through the water." This is a specific example of oneadaptation that these fish have made to increase their swimming efficiency. None of the otherchoices is mentioned in the paragraph.
6. ○ 1
This is a Factual Information question asking for specific information that can be found in thepassage. The correct answer is choice 1, "They lack a swim bladder." Paragraph 6 explicitlystates ". . . tunas must swim to breathe. They must also keep swimming to keep from sinking,since most hale largely or completely lost the swim bladder . . ." The other choices are notsupported by the passage.
7. ○ 4
This is a Sentence Simplification question. As with all of these items, a single sentence in thepassage is highlighted:
One potential problem is that opening the mouth to breathe detracts from the
streamlining of these fishes and tends to slow them down.
The correct answer is choice 4. That choice contains all of the essential ideas in the highlightedsentence. It is also the only choice that does not change the meaning of the sentence. It omitsthe fact that this is "a problem” and also "that it detracts from streamlining" because thatinformation is not essential to the meaning.
Choice 1 says that these fish have trouble opening their mouths while swimming, which is nottrue. Choice 2, that streamlining prevents fish from slowing down, may be true, but it is notmentioned in this sentence. The fish are slowed down when they open their mouths, whichreduces streamlining. Choice 3, that streamlining slows the fishes' breathing, is also notmentioned.
8. ○ 3
This is a Vocabulary question. The word being tested is channel. It is highlighted in thepassage. The correct answer is choice 3, "direct." Channel here is used as a verb, meaning to"move" or "push."
9. ○ 2
This is a Factual Information question asking for specific information that can
be found in the passage. The correct answer is choice 2, "make efficient use of
water currents." Paragraph 8 explicitly states: "Perhaps most important of all to
these and other fast swimmers is their ability to sense and make use of swirls and
eddies (circular currents) in the water. They can glide past eddies that would slow
them down and then gain extra thrust by "pushing off" the eddies. Scientists and
engineers are beginning to study this ability of fishes in the hope of designing
more efficient propulsion systems for ships." The other choices are not mentioned
in connection with the performance of ships.
10. ○ 3
This is a Factual Information question asking for specific information that can be found inparagraph 9. The correct answer is choice 3, "They can swim in waters that are much colderthan their own bodies." That paragraph says, "A bluefin tuna in water of 7°C (45°F) canmaintain a core temperature of over 25°C (77"F)." So it is clear that choice C is ce 1 is not stated in the paragraph. Choice 2 is contradicted by the paragraph. Choice 4 istrue of billfish, not bluefin tuna.
11. ○2
This is an Insert Text question. You can see the four black squares in paragraph 6 thatrepresent the possible answer choices here. The last sentence of paragraph 5 is alsoreproduced below.
Again, supersonic jets have similar features. ■Because they are always swimming, tunas simplyhave to open their mouths and water is forced in and over their gills. ■ Accordingly, they havelost most of the muscles that other fishes use to suck in water and push it past the gills. Infact, tunas must swim to breathe.■They must also keep swimming to keep from sinking, sincemost have largely or completely lost the swim bladder, the gas-filled sac that helps most otherfish remain buoyant.
The sentence provided, "Consequently, tunas do not need to suck in water," is best inserted atsquare 2. The sentence provides an explanation for the muscle loss described in the sentencethat follows square 2 and is a result of the fact described in the preceding sentence, which saysthat because the fish are always swimming, they only have to open their mouths to suck inwater. Thus if the provided sentence is inserted at square 2, it provides a logical bridgebetween cause and effect. The sentence makes no logical sense anywhere else.
12. ○Reducing Water Resistance: 1 4 5; Increasing Thrust: 2 7
This is a Fill in a Table question. It is completed correctly below. The correct choices for the"Reducing water resistance" column are 1, 4, and 5. Choices 2 and 7 belong in the "Increasingthrust" column. Choices 3 and 6 should not be used in either column.
金槍魚，鯖魚，和長嘴魚(或者說成是槍魚、旗魚和箭魚)的遊動從不停止。它們的進食，求偶，繁殖，甚至“休息”都在不斷的運動中進行。事實上，這些游泳“機器”身體結構的每個部位及其功能都有利於它們更好地遊行。
爲了減少在水中前行的阻力，這類魚身上產生了很多適應性變化。非常有趣的是，人類爲了降低空氣阻力加快高速飛機運行速度所進行的設計和這些魚的適應性變化非常相似。這種設計只是人類工程師的初步嘗試，但金槍魚和他們的同類們已經擁有這種“高科技”設計很久很久。
金槍魚、鯖魚和長嘴魚的流線體型簡直就是一件工藝品。他們的身體光滑而堅實。從工程師的角度來看，金槍魚的體型近乎完美。很多魚類的絕大多數皮膚上是沒有魚鱗的，特別光滑。它們的眼睛和身體處於同一平面，根本不會凸顯出來。身體表面還覆蓋着一層光滑透明的外衣，魚鰭部分堅硬、平穩而狹窄，這些特徵都有助於降低前行中的阻力。當魚兒們不使用魚鰭時，會將它們折回到特殊的溝槽或者凹陷的地方，與身體保持同一平面，以維持它們平滑的外形。飛機收回起落裝置，和這是同樣的道理。
和上述特徵相比，金槍魚、鯖魚和長嘴魚們擁有更加精明的手段來增加它們在水中的適應性，比如他們的大長嘴。很多超音速飛機的頭部就有類似的針狀設計。
大多數金槍魚和長嘴魚的尾巴附近會長有一串脊骨和小鰭。雖然它們身上大部分地方是無鱗的，但在頭部附近還保留着一塊較粗的鱗片，叫做(魚的')胸甲。脊骨、小鰭和胸甲有助於水直接流經魚體表面，降低阻力(見附圖)。同樣，超音速飛機的噴頭也有類似的特徵。
因爲金槍魚的遊動從不停止，它們必須張着嘴使水流經它們的腮。而其他魚類的嘴裏都會有一塊肌肉，用於吸水和從腮裏排水，金槍魚的這塊肌肉已經退化。實際上，它們必須通過游泳來呼吸。大部分金槍魚很大程度上已經喪失了其他魚類用於保持漂浮狀態的魚鰾，或者說已經完全喪失，因此，它們必須保持持續游泳的狀態。
一個可能存在的問題在於，金槍魚張嘴呼吸破壞了它們的流線型體型，有可能會降低它們的游泳速度。爲此有的金槍魚會在舌頭上長有特殊的凹槽，以便引導水流通過嘴巴從腮縫流出，從而減少了阻力。
和降低阻力一樣，金槍魚們在游泳動力的加強上也有產生適應性變化。人類工程師在他們面前不得不自嘆不如。向後傾斜並且長而狹窄的尾部非常有利於它們用最省力的方式前行。對這些魚兒以及其他的魚類游泳健將們來說，要保持在水裏快速前行，最重要的可能就是對漩渦和逆流感知及利用的能力。漩渦會降低它們的速度，但它們在流經漩渦時不僅可以輕而易舉地滑過而且會通過“推動”漩渦獲得額外的動力。科學家和工程師們正在研究魚的這種能力，以期設計出更高效的輪船推進系統。
這些魚類的肌肉組織和保溫機制也非常高效。一隻藍鰭金槍魚在7°C (45°F)的溫度下可以保持25°C (77°F)以上的體溫。溫暖的體溫可以使得肌肉、大腦和眼睛更好地運轉。長嘴魚更厲害。它們有專門改善肌肉組織的加熱器，可以使眼睛和大腦保持一定溫度，從而保證自己的重要的器官保持在最好的運行狀態中。
