語氣助動詞 – Must

Must 最常用來表示推測的「一定,肯定,想必,諒必」,後接 BE 動詞,現在式為 must be,過去式為 must have been/P.P.。它亦可用來表示義務、責任、要求的「必須」(過去式變成 had to),不過母語人士比較喜歡使用較有彈性的 have to。此外,它還可表示強烈建議的「應該」。Must not 或 mustn’t 是在表示「禁止,不准,不得」,不是表示「推測」,但這聽起來非常嚴厲,最好改用語氣比較柔和的 should not 或 ought not 來勸阻而非禁止。

例句:

  • Kevin must be nearly 60 years old now. (凱文現在肯定快 60 歲了) - 肯定的推測
  • You must do what you should do. (你必須做你應該做的事) - 義務、責任、要求
  • You must go and see that movie. It is really amazing! (你應該去看那部電影。真的太棒了! ) - 強烈建議
  • Sam, you must not talk like that. (山姆,你不許那樣說話) - 禁止

注意:關於推測的否定式,現在式用 can’t + BE 動詞,而過去式用 can’t/couldn’t + have + been/P.P.,意為「一定不;一定未;一定沒有」。說得更明確一點,表示「推測」的 must,肯定時用 must + BE 動詞或 must + have + been/P.P.,否定時用 can’t + BE 動詞或 can’t/couldn’t + have + P.P.,我們不可在 must 後面直接加 not,因為 must not 或 mustn’t 是表示「禁止,不准」,不是表示「推測」。

Must 的現在、過去和未來時態用法

大多數語氣助動詞的過去和未來時態都相當不規則。下表為 must 在不同上下文中的用法說明。

Must 的用法肯定句否定句你也可以用
肯定的推測現在:That must be Emma. They said she was pretty with fair skin and hair. (那一定是艾瑪。他們說,她長得漂亮,而且皮膚白皙,有一頭金色頭髮)
過去:Why didn't you answer my phone call? (你為什麼沒有接我的電話?)
Well, I must have been sleeping, so I didn't hear it. (哦,我 [當時] 一定正在睡覺,所以沒有聽到電話響)
未來:沒有未來式。
現在:Must 變成 can
That can't be Emma. She is supposed to be pretty and have fair skin and hair. (那一定不是艾瑪。她應該長得漂亮,而且皮膚白皙,有一頭金色頭髮)
過去:Must 變成 can/could
David can't have found his car, for he came to work by bus this morning. (大衛一定還沒有找到他的車,因為早上他是坐公車來上班的)
未來:沒有未來式。
have to
義務、責任、要求 (美國人比較喜歡使用 have to)現在:You must have a membership card to enter the fitness center. (你必須有會員卡才能進入這家健身中心)
過去:Must 變成 have to
You had to have a membership card to enter the fitness center. (你必須有會員卡才能進入這家健身中心)
未來:You must get a membership card to enter the fitness center next week. (你下週必須有會員卡才能進入這家健身中心)
現在:Must 變成 have to
You don't have to get a membership card to enter the fitness center. (你不必有會員卡就能進入這家健身中心)
過去:Must 變成 have to
You didn't have to get a membership card to enter the fitness center. (你不必有會員卡就能進入這家健身中心)
未來:Must 變成 have to
You won't have to get a membership card to enter the fitness center next week. (你下週不必有會員卡就能進入這家健身中心)
have to
強烈建議 (美國人比較喜歡使用 should)現在:You must take a day off to get some rest. (你應該請一天假休息一下)
過去:Must 變成 should
You should have taken a day off last week to get some rest. (你上週應該請一天假休息一下) - 實際上並沒有請假。
未來:Must 變成 should
You should take a day off next week to get some rest. (你下週應該請一天假休息一下)
現在:Must 變成 should
You shouldn't smoke too much. It's not good for your health. (你不應抽太多菸。這對你的健康不好)
過去:Must 變成 should
You shouldn't have smoked too much. It caused lung cancer. (你不應抽太多菸。那導致肺癌)
未來:Must 變成 should
You shouldn't smoke in the conference room. The president will hold a meeting there ten minutes later. (你不應在會議室抽菸。十分鐘後董事長就要在那裡開會)
should
禁止The robbers must not go unpunished. (絕不能讓這些搶匪逍遙法外)
We mustn't smoke in the office. (我們不准在辦公室抽菸)

禁止通常指不久的將來。

注意:“Must not” 和 “Do not have to” 的意思並不相同。Must not 意為「禁止,不准,不得」,而 Do not have to 意為「不必」。

例句:

  • You must not drink that beer. (你不許喝罐啤酒) - 你被禁止喝那罐啤酒。
  • You don’t have to drink that beer. (你不必喝罐啤酒) - 如果你想喝那罐啤酒的話可以喝,但並非必須的。
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One Comment

  1. 這篇教學很實用,學會must亦知道should等等分別, tenses及規則(eg必須轉can’t be不能must not),該注意重點都齊,不是只有例句然後要你自行領悟,而例句亦用相同的看出比較,受益良多

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