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Caffeine is the bitter stimulant in coffee beans, tea leaves, , kola nut, and guarana, and the one added to many colas and energy drinks. It helps you feel awake by blocking a brain signal that says you are tired — which is also why too much can leave you shaky, sleepless, or with a racing heart.
Caffeine is the bitter stimulant in coffee beans, tea leaves, cacao, kola nut, and guarana咖啡因是存在咖啡豆、茶葉、可可、可樂果、和瓜拿納裡的一種苦味興奮劑 and the one added to many colas and energy drinks也是很多可樂和能量飲料裡添加的成分。It helps you feel awake by blocking a brain signal that says you are tired它會擋住大腦裡「你累了」的訊號，讓你感覺清醒 which is also why too much can leave you shaky, sleepless, or with a racing heart這也是為什麼喝太多會讓人手抖、睡不著、或心跳加快
It is a mild everyday drug, legal, and used by huge numbers of adults. Amounts vary more than people think: a large drip coffee can hold more than a small ; tea is usually less; chocolate has a little. is not zero, just much less.
It is a mild everyday drug它是一種溫和的日常藥物 legal, and used by huge numbers of adults合法，而且非常多成年人都在使用。Amounts vary more than people think含量的差異比大家想的還要大 a large drip coffee can hold more than a small espresso一杯大杯的美式滴濾咖啡可能比一小杯濃縮咖啡含量還高 tea is usually less茶通常含量比較少 chocolate has a little巧克力也含有一點點。Decaf is not zero低咖啡因(decaf)不是完全零咖啡因 just much less只是少很多
Two , CAF-een, not caf-AY-in. A classroom word and a packet word; everybody meets it.
Two syllables, CAF-een兩個音節，唸CAF-een not caf-AY-in不是唸caf-AY-in。A classroom word and a packet word這是課堂上會教、包裝上也會印的字 everybody meets it每個人都會遇到它
組成From the word for coffee — French caféine, or German Kaffein from Kaffee — plus the chemical suffix -ine. Café / Kaffee themselves go back through Italian caffè.
同家族的字
- coffeethe drink whose name the stimulant was taken from
- caféthe French coffee word inside caféine
- caffeinatedthe adjective: containing this stimulant
- decafeveryday short form for coffee with most of the caffeine removed
原始詞典資料1 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
caffeinenoun/ˈkæfiːn/
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An alkaloid, C₈H₁₀N₄O₂, found naturally in tea and coffee plants, which acts as a mild stimulant on the central nervous system.
- For example, 0.100 grams of caffeine yield by combustion, by weight, 0.180 grammes of carbonic acid.
- Hitherto, in consequence of its slight solubility, caffeine has been administered hypodermically only in very small doses ; in fact, at the ordinary temperature, it requires 93 parts of water to dissolve, so that a cubic centimeter would contain scarcely more than a centigram.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。