How Did People Reach the Americas?( 第二段 )

1. How Did People Reach the Americas?(第二段) 第一組

2. 段落翻譯 • Rewriting the prehistory of the Americas is perhaps the most remarkable discovery─but hardly the only one─so far achieved through the analysis of ancient DNA. Other new insights about the past are being drawn from the same emerging scientific discipline. • 改寫美國史前史也許是最驚人的發現──但恐怕不會是唯一一個至今所取得的──通過分析古老的DNA。有關過去的其他新的見解來自同一新興的科學學科(分析古老的DNA)。

3. In the past five years, the double helix has shed light, for example, on the vanished wooly mammoth, the flightless dodo, and even humanity's long-lost kin, the Neanderthals. • 在過去五年,雙股螺旋的研究已經有重大的進展。舉例而言,已消失的長毛象,不能飛的度度鳥,甚至是人類血緣關係失散已久的尼安德塔人。這些研究都有了新的突破。

4. Extracting and testing old DNA, once considered practically impossible because too little of the stuff survives the eons intact, are now at the cutting edge of archaeology, paleontology, and other fields, thanks to new techniques and more powerful technology. • 以前認為抽出並檢測古老DNA是幾乎不可能的，因為太少的材料是可以恆久的存在並且完好無缺的，但有了最先進的考古學、古生物學及其他領域的進步後，使得這項技術可以實現了。這都由於新的技術和更有力的科技。

5. Main Idea • This paragraph explains how the people discover and study archaeology, paleontology, and other fields with new DNA techniques.

6. 單字 • Prehistory [pri`hɪstərɪ]史前背景(n.) • Pre- Preadolescence 青少年期 Precancerous未成為癌症的 Precondition 先決條件 Prearrange 事前安排 Predigest 預先消化 • Remarkable [rɪ`mɑrkəb!]引人注目的(adj.) • 相似詞 Extraordinary 特別的 Exceptional 特別的 • Discipline [`dɪsəplɪn]方法;紀律;訓練;學科 (n.)

7. Woolly [`wʊlɪ] 模糊的;羊毛的(adj.) Wooly 粗獷的;羊毛的 • Woolly mammoth [`wʊlɪ] [`mæməθ]長毛象(n.) • Flightless [`flaɪtlɪs]不能飛的(adj.) • -less Careless 不小心的 Homeless 無家可歸的 Nonetheless 雖然如此;但是 • Dodo [`dodo]渡渡鳥(古代巨鳥) (n.) • Kin(+to) [kɪn]同類;親屬(n.) • Neanderthal [`nɪ`ændɚ,tɑl]穴居人(尼安德人) (n.) (adj.) • Extract [ɪk`strækt]提煉(v.) • Test [`tɛstɪŋ]化驗(v.)

8. Eon [`iən]永世(n.) • Intact [ɪn`tækt]原封不動的(adj.) • Practically [`præktɪk!ɪ]幾乎;事實上(adv.) Almost 幾乎 • Archeology [͵ɑrkɪ`ɑlədʒɪ]考古學(n.) • Paleontology [͵pelɪɑn`tɑlədʒɪ]化石學(n.) • Technique [tɛk`nik]技術(n.)

9. DNA • Deoxyribonucleic acid, or DNA, is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms with the exception of some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

10. DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.

11. Within cells, DNA is organized into long structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts.In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

12. 句型 • So far 到目前為止 so far so good 目前尚可 • Thanks to + N. 幸虧;由於 = Due to +N.= Owing to N.=Because of + N.= On account of + N.

13. Consider用法 • consider + N. ex: We consider his suggestion. • consider + Ving ex: He is considering going to study abroad. • consider + O + (to be) 認為…是… = think of A as B = regard A as B = view A as B ex: I consider him (to be) my best friend. • consider that + 子句

14. 文法 • has/have + p.p. 可連接副詞- 現在剛完成之動作: just , recently , already , so far , yet 表經驗: never , ever , once , …times 長連接副詞: for + 一段時間 , since + 時間點 • 動名詞當主詞 1.Rewriting the prehistory of the Americas is perhaps … 2.Extracting and testing old DNA, once considered practically impossible because too little of the stuff survives the eons intact, are now at …

15. 被動語態 • am/is/are + being + p.p. 現在進行式的被動 • was/were + being + p.p. 過去進行式的被動 最高級 • the most + 形容詞最高級 • 修飾最高級的副詞: the very/much the/by far

16. Thoughts • Because this paragraph is just the beginning of the essay, there are not too many things I can tell. The only thought I would like to tell is that the human has to thank for the development of the technology and techniques that make us discover and gradually understand the prehistory of America.