必須與不必(must / have to)

🎯 這一課你會學會

講規定和義務——什麼「必須」做、什麼「不准」做、什麼「不必」做。用 must / mustn't 和 have to / don't have to。這裡有一個超容易錯的區別,這課幫你分清楚。

💬 先聽一段對話

Boss: You have to finish this by Friday.（你必須週五前完成。) Jun: OK. Do I have to come to the meeting too?（好。我也必須去開會嗎?) Boss: No, you don't have to. It's optional.（不用,可去可不去。) Boss: But you mustn't share these files. They're private.（但你不准分享這些檔案。是機密。)

🔑 關鍵句型

• must + 原形(必須,強制)/ mustn't + 原形(不准,禁止)。
• have to + 原形(必須)/ don't have to + 原形(不必,可做可不做)。
• 問句(have to):Do you have to…?　→ Yes, I do. / No, I don't.

🧩 文法點:兩組「必須」+ 最關鍵的區別

① must / have to:兩個都是「必須」,日常多用 have to

• You must wear a seatbelt.（你必須繫安全帶。)
• I have to work tomorrow.（我明天必須上班。)
• 差別很小:must 常用在規則、標示、強烈要求;have to 用在一般的必須。口語 have to 更常見。
• have to 會變:he/she has to(第三人稱);過去 had to。must 不變、也沒有過去式。

② ⚠ mustn't ≠ don't have to(這是重點,professor 一定考)

• mustn't = 不准、禁止(不可以做):You mustn't park here.（不准停這。)
• don't have to = 不必、非強制(可做可不做):You don't have to park here.（你不一定要停這——但可以。)
• 中文都能說「不用」,英語差很多:一個是禁止、一個是沒必要。別搞混。

③ 都接原形動詞、都對所有主詞一樣(have to 除外要變 has to):

• ✅ She must go. / She has to go.　❌ She must to go / She must goes.

📒 高頻單字

單字	KK 音標	中譯	例句
must	/mʌst/	必須	You must try.（你一定要試。)
rule	/rul/	規則	It's a rule.（這是規定。)
wear	/wɛr/	穿、戴	wear a mask（戴口罩)
private	/ˈpraɪvɪt/	私人的	It's private.（這是私人的。)
optional	/ˈɑpʃənəl/	可選的	It's optional.（可做可不做。)

🗣️ 發音提醒

• mustn't /ˈmʌsənt/:中間的 t 不發音,唸「MUS-ənt」。
• have to 口語常唸 /ˈhæftə/(「hafta」);has to → /ˈhæstə/(「hasta」)。
• wear /wɛr/ 跟 where 同音;跟 we're /wɪr/ 不同。

✍️ 開口練習

練習 1:mustn't 還是 don't have to?

• 這是機密,你「不准」講 → You ＿ tell anyone.（mustn't)
• 明天放假,你「不必」來 → You ＿ come tomorrow.（don't have to)

練習 2:has to 還是 have to?

• I ＿ work.（have to)　She ＿ study.（has to)　They ＿ leave.（have to)

練習 3:講三條你生活裡的規定。

At work / school / home, I have to ＿. I mustn't ＿. I don't have to ＿.

🎒 帶走

• must / have to = 必須(日常多用 have to;has to / had to 會變)。
• mustn't(禁止,不准)≠ don't have to(不必,可做可不做)——最關鍵的區別。
• 都接原形動詞。

下一課,語氣放軟一點:should / shouldn't——給建議、講「應該不應該」。