3. Diamonds are made from carbon.

由……制成，可以用be made from和be made of兩個詞組來表達。但是be made from通常指制成品已看不出原材料是什么，而be made of可以看出該物品由什么材料制成的。

4. Scientists know that the combination of extreme heat and pressure changes carbon into diamonds.

extreme在句中做形容詞用，意思是“極度的”，如：

1) Extreme cold can wake a hibernating animal. (極度的寒冷能使正在冬眠的動物蘇醒。)

2) They will have to endure extreme discomfort in winter. (冬天時，他們將不得不忍受極度的不適。)

change…into意思是“把…轉變為…”，如：

1) Water changes into vapour when heated. (水加熱后轉變為蒸氣。)

2) Go to the bank and you can easily change these dollars into RMB. (你去銀行就能很容易地把這些美元換成人民幣。)

5. Such heat and pressure exist only in the hot， liquid mass of molten rock deep inside the earth.

請注意such與so之間的不同用法。such后面接名詞，而so后面接形容詞或副詞。如：

1) I don't believe he could make such a mistake. (我相信他不會犯這樣的錯誤的。)

2) How can you go out on such a rainy day? (在這樣的雨天里，你怎么能出門?)

3) He spoke so fast that I couldn't follow. (他說話太快，我聽不懂。)

4) I'm so glad you could come. (你能來我真高興。)

mass在本句中的意思是“(聚成一體的)團、塊”，比如：

1) a mass of hot air(一團熱氣)

2) a mass of sand(一堆沙)

3) Rain occurs when a mass of warm air is laden with water. (一團云聚集大量的水蒸氣就形成了雨。)

Mass也可以做形容詞用，意思是“群眾的”、“大量的”，如：

1) a mass meeting (群眾大會)

2) mass education (大眾教育)

3) mass media (大眾傳媒)

4) Mass production could very well cut the cost. (大規模生產可以降低成本。)