📖 原文
(1) Anyone who has handled a fossilized bone knows that it is usually not exactly like its (2) modern counterpart, the most obvious difference being that it is often much heavier. (3) Fossils often have the quality of stone rather than of organic materials, and this has led (4) to the use of the term "petrifaction" (to bring about rock). The implication is that (5) bone, and other tissues, have somehow been turned into stone, and this is certainly the (6) explanation given in some texts. But it is a wrong interpretation; fossils are frequently so (7) dense because the pores and other spaces in the bone have become filled with minerals (8) taken up from the surrounding sediments. Some fossil bones have all the interstitial (9) spaces filled with foreign minerals, including the marrow cavity, if there is (10) one, while others have taken up but little from their surroundings. Probably all of the (11) minerals deposited within the bone have been recrystallized from solution by the action (12) of water percolating through them. The degree of mineralization appears to be determined by the nature of the environment in which the bone was deposited and not by (13) the antiquity of the bone. For example, the black fossil bones that are so common in many parts of Florida are heavily mineralized, but they are only about 20,000 years old, whereas many of the dinosaur bones from western Canada, which are about 75 million years old, are only partially filled in. Under optimum conditions the process of (14) mineralization probably takes thousands rather than millions of years, perhaps (15) considerably less. (16) The amount of change that has occurred in fossil bone, even in bone as old as that of (17) dinosaurs, is often remarkably small. We are therefore usually able to see the microscopic (18) structure of the bone, including such fine details as the lacunae where the living bone cells (19) once resided. The natural bone mineral, the hydroxyapatite, is virtually unaltered too — it has the same crystal structure as that of modern bone. Although nothing remains of the original collagen, some of its component amino acids are usually still (20) detectable, together with amino acids of the noncollagen proteins of bone.
❓ 试题解析
问题 21： What does the passage mainly discuss?
A. The location of fossils in North America
B. The composition of fossils
C. Determining the size and weight of fossils
D. Procedures for analyzing fossils
✅ 正确答案： B）The composition of fossils
📝 解析： 全文讨论化石骨骼的成分变化：矿化作用、矿物填充、胶原蛋白残留等。
💡 解题技巧： 主旨题看首段主题句及全文反复出现的关键词（mineralization, bone, fossil）。
问题 22： The word "counterpart" in line 2 is closest in meaning to
A. species
B. version
C. change
D. material
✅ 正确答案： B）version
📝 解析： "modern counterpart" 指现代版本的骨骼，counterpart = 对应物/版本。
💡 解题技巧： 词汇题：某物的对应物或相似物。
问题 23： Why is fossilized bone heavier than ordinary bone?
A. Bone tissue solidifies with age.
B. The marrow cavity gradually fills with water.
C. The organic materials turn to stone.
D. Spaces within the bone fill with minerals.
✅ 正确答案： D）Spaces within the bone fill with minerals.
📝 解析： 文中明确说"pores and other spaces in the bone have become filled with minerals"。
💡 解题技巧： 因果细节题定位"because"或解释原因的结构。
问题 24： The word "pores" in line 7 is closest in meaning to
A. joints
B. tissues
C. lines
D. holes
✅ 正确答案： D）holes
📝 解析： 孔隙是骨头中的小洞，矿物质进入填充。
💡 解题技巧： 词汇题结合上下文"filled with minerals"推断。
问题 25： What can be inferred about a fossil with a high degree of mineralization?
A. It was exposed to large amounts of mineral-laden water throughout time.
B. Mineralization was complete within one year of the animal's death.
C. Many colorful crystals can be found in such a fossil.
D. It was discovered in western Canada.
✅ 正确答案： A）It was exposed to large amounts of mineral-laden water throughout time.
📝 解析： 矿化程度取决于环境，水渗透携带矿物质填充骨骼。
💡 解题技巧： 推理题结合"minerals deposited ... by water percolating"。
问题 26： Which of the following factors is most important in determining the extent of mineralization in fossil bones?
A. The age of the fossil
B. Environmental conditions
C. The location of the bone in the animal's body
D. The type of animal the bone came from
✅ 正确答案： B）Environmental conditions
📝 解析： "The degree of mineralization appears to be determined by the nature of the environment"。
💡 解题技巧： 细节题找明确陈述（determined by）。
问题 27： Why does the author compare fossils found in western Canada to those found in Florida?
A. To prove that a fossil's age cannot be determined by the amount of mineralization
B. To discuss the large quantity of fossils found in both places
C. To suggest that fossils found in both places were the same age
D. To explain why scientists are especially interested in Canadian fossils
✅ 正确答案： A）To prove that a fossil's age cannot be determined by the amount of mineralization
<>📝 解析： 佛罗里达的化石更年轻但矿化更重，证明矿化程度与年代无关。
💡 解题技巧： 例证题看例子前的论点句（"not by the antiquity of the bone"）。
问题 28： The word "it" in line 24 refers to
A. hydroxyapatite
B. microscopic structure
C. crystal structure
D. modern bone
✅ 正确答案： A）hydroxyapatite
📝 解析： "The natural bone mineral, the hydroxyapatite, is virtually unaltered too — it has the same crystal structure..." — it 指 hydroxyapatite。
💡 解题技巧： 代词题找同位语或前一个名词短语。
问题 29： The word "detectable" in line 26 is closest in meaning to
A. sizable
B. active
C. moist
D. apparent
✅ 正确答案： D）apparent
📝 解析： 氨基酸仍然"可检测到"，即明显可见，apparent。
💡 解题技巧： 词汇题：detectable = able to be noticed or found。
问题 30： Which of the following does NOT survive in fossils?
A. Noncollagen proteins
B. Hydroxyapatite
C. Collagen
D. Amino acid
✅ 正确答案： C）Collagen
📝 解析： "Although nothing remains of the original collagen, some of its component amino acids ... still detectable"。
💡 解题技巧： "NOT"题定位否定词（nothing remains）。
🌐 中文翻译
任何处理过化石骨骼的人都知道，它通常不完全像现代版本的骨骼，最明显的区别是它往往重得多。化石常常具有石头而非有机材料的特性，这导致了"petrifaction"（石化）一词的使用。其含义是骨骼和其他组织以某种方式变成了石头，这确实是一些文本中给出的解释。但这是一个错误的解释；化石之所以常常如此致密，是因为骨骼中的孔隙和其他空间被从周围沉积物中吸收的矿物质填充了。有些化石骨骼的所有间隙空间都被外来矿物质填充，包括髓腔（如果有的话），而另一些则仅从周围环境中吸收了很少的矿物质。骨骼内沉积的矿物质很可能都通过渗透其中的水的作用，从溶液中再结晶。 矿化程度似乎取决于骨骼沉积的环境性质，而不是骨骼的年代。例如，佛罗里达许多地区常见的黑色化石骨骼矿化程度很高，但它们只有约2万年的历史，而来自加拿大西部的许多恐龙骨骼约有7500万年历史，却只是部分填充。在最佳条件下，矿化过程可能只需要数千年而非数百万年，或许还要少得多。 化石骨骼中发生的变化量，即使是像恐龙骨骼那样古老的化石，也常常非常小。因此我们通常能够看到骨骼的显微结构，包括活骨细胞曾经所在的骨陷窝等精细细节。天然骨矿物质羟基磷灰石也几乎没有改变——它具有与现代骨骼相同的晶体结构。虽然原始的胶原蛋白已不存在，但其某些组成氨基酸通常仍然可检测到，同时还有骨骼中非胶原蛋白的氨基酸。
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