跟讀練習: Lesson 7: Valency and Chemical Formulae - 通過影片學習英語口語
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11 句
如果句子過短或過長，請點選 Edit 進行調整。
1
A chemical formula shows which elements make up a substance, and the number of atoms of each element.
2
We use the symbols of chemical elements and subscripts to write chemical formulae for simple substances and compounds.
3
A subscript shows the number of atoms of an element in a chemical formula.
4
Valency describes the combining ability of an atom or a group of atoms.
5
To write a chemical formula, we use the valencies of the elements and apply the valency rule.
6
The valency rule helps us write the correct chemical formula of a compound.
7
In sulfur dioxide, the valency of sulfur is 4, and the valency of oxygen is 2.
8
So the formula is SO2.
9
The molecular mass is the sum of the atomic masses of all the atoms in a molecule.
10
The percentage by mass of an element is calculated by dividing its total mass by the molecular mass of the compound, then multiplying by 100%.
11
We can determine a chemical formula from the percentage composition of its elements and its molecular mass.
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本課的詞彙與口語要點
這節口語課以影片“Lesson 7: Valency and Chemical Formulae”為素材。 影片中反覆出現的詞有：element, chemical, formula, valency, atom。 這段影片共有 11 個句子、170 個單詞可供跟讀。 講話部分時長為 1:00。 說話人語速自然，每分鐘約 170 個詞，接近日常對話。 只有 66% 的單詞屬於英語最常用的 3,000 詞，詞彙難度較高。
影片中的重點詞彙
影片中 15 個值得學習的單詞，附發音和釋義：
| 單詞 | 發音 | 釋義 |
|---|---|---|
| element 名詞 | /ˈɛləmənt/ | 要素 |
| formula 名詞 | /ˈfɔː.mjʊ.lə/ | 公式 |
| atom 名詞 | /ˈætəm/ | 原子 |
| compound 名詞 | /ˈkɑmpaʊnd/ | 化合物 |
| percentage 名詞 | /pə(ɹ)ˈsɛntɪd͡ʒ/ | 百分率, 百分比 |
| substance 名詞 | /ˈsʌbstəns/ | 物質 /物質 |
| composition 名詞 | /ˌkɑm.pəˈzɪʃ.ən/ | 成分 |
| symbol 名詞 | /ˈsɪmbəl/ | 符號 /符號 |
| oxygen 名詞 | /ˈɑksɪd͡ʒən/ | 氧 |
| combine 動詞 | /kəmˈbaɪn/ | 結合 /結合, 組合 /組合 |
| divide 動詞 | /dɪˈvaɪd/ | 分, 分裂 |
| atomic 形容詞 | /əˈtɑː.mɪk/ | 原子 |
| calculate 動詞 | /ˈkælkjʊleɪt/ | 計算 /計算, 算 |
| dioxide 名詞 | /daɪˈɑksaɪd/ | 二氧化物 |
| molecule 名詞 | /ˈmɑ.lɪ.kjul/ | 分子 |
影片中出現的短語動詞
| 單詞 | 發音 | 釋義 |
|---|---|---|
| make up 動詞 | /ˌmeɪk ˈʌp/ | 組成 /組成 |
影片中的語法
說話人最常用的結構，並附上影片中的原話：
| 結構 | 影片中的用法 |
|---|---|
| 被動語態 be + 過去分詞 — 強調發生了什麼，而不是誰做的 | is calculated |
需要注意的發音
- 長單詞——注意重音位置: molecular /məˈlɛk.jə.ləɹ/, composition /ˌkɑm.pəˈzɪʃ.ən/
中文母語者容易讀錯的音：
- /v/ — 不要讀成 /w/，上齒輕觸下唇: divide /dɪˈvaɪd/, valency /ˈveɪ.lən.si/
- 詞尾子音 — 要讀清楚，後面不要加母音: element /ˈɛləmənt/, compound /ˈkɑmpaʊnd/, percentage /pə(ɹ)ˈsɛntɪd͡ʒ/, substance /ˈsʌbstəns/, divide /dɪˈvaɪd/
- /æ/ — 嘴張大，不要讀成 /e/: atom /ˈætəm/, calculate /ˈkælkjʊleɪt/
如何用這段影片練習
- 先完整聽一遍影片，不要開口，記下不認識的單詞。
- 先用 0.75 倍速逐句跟讀，熟練之後再回到正常速度。
- 錄下自己的聲音並與原聲對比，特別注意 element, formula, atom 這類單詞。
什麼是跟讀法？
跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧，最初開發用於專業口譯員的培訓，並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大：您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同，跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性，語調，節奏，連讀，聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。