Sub-zero means below zero degrees — colder than the point where water freezes. It is an adjective and normally goes in front of a noun: sub-zero temperatures, sub-zero conditions, a sub-zero night. You would not usually say "the weather was sub-zero" on its own; "the temperature was below zero" is the natural way to say that.

Sub-zeroSub-zero means指的是 below zero degrees零度以下 — colder than the point where water freezes比水結冰的溫度還冷。It is它是 an adjective形容詞, and而且 normally goes in front of a noun通常放在名詞前面: sub-zero temperatures, sub-zero conditions, a sub-zero nightsub-zero temperatures、sub-zero conditions、a sub-zero night。You would not usually say你通常不會單獨說 'the weather was sub-zero' on its own「the weather was sub-zero」; 'the temperature was below zero'「the temperature was below zero」 is the natural way to say that才是自然的說法。

It sounds slightly technical and dramatic, which is why weather reports, news stories, and product advertising like it. Coats, sleeping bags, and car batteries are sold as suitable for sub-zero conditions.

It sounds它聽起來 slightly technical and dramatic有點專業又戲劇化, which is why這也是為什麼 weather reports, news stories, and product advertising氣象報告、新聞和產品廣告 like it都愛用它。Coats, sleeping bags, and car batteries外套、睡袋和汽車電瓶 are sold as suitable for都會標榜適合 sub-zero conditionssub-zero conditions。

Writers also stretch it away from weather to describe a person who is extremely cold in manner: sub-zero politeness, a sub-zero stare. That use is figurative and fairly rare, but you will meet it.

Writers also作家也會 stretch it away from weather把它從天氣的意思延伸出去, to describe a person用來形容一個人 who is extremely cold in manner態度極度冷淡: sub-zero politeness, a sub-zero staresub-zero politeness、a sub-zero stare。That use這種用法 is figurative and fairly rare是比喻性的，也相當少見, but但 you will meet it你還是有可能遇到。

One thing worth knowing, and it matters for a student in Taiwan reading international news: which zero? In Celsius, zero is freezing point, so sub-zero and freezing mean roughly the same thing. In Fahrenheit, zero is about -18°C, so an American saying "sub-zero" is describing something far, far colder than a British writer usually means. Most writing outside the United States assumes Celsius, but if the number matters, check the scale.

One thing worth knowing有一件值得知道的事, and it matters for a student in Taiwan reading international news對在臺灣讀國際新聞的學生特別重要: which zero是哪一種零度? In Celsius在攝氏裡, zero is freezing point零度是結冰點, so所以 sub-zero and freezing meansub-zero跟freezing大致上是 roughly the same thing同一件事。In Fahrenheit在華氏裡, zero is about -18°C零度大約是攝氏零下18度, so所以 an American saying 'sub-zero'美國人說「sub-zero」時 is describing something指的東西 far, far colder than a British writer usually means比英式作者通常講的還要冷得多。Most writing outside the United States美國以外的文章 assumes Celsius大多預設用攝氏, but但 if the number matters如果數字很重要, check the scale就要確認一下用的是哪個溫標。

Note also that it is written with a hyphen most of the time, though subzero appears too, especially in American writing.

Note also另外要注意, that it is written with a hyphen most of the time它大多數時候是用連字號寫成sub-zero, though不過 subzero appears toosubzero這種寫法也會出現, especially尤其是 in American writing在美式寫作裡。