have to與must這兩個動詞均有「必須、不得不」之意。
have to : 通俗用語,指受客觀條件或環境迫使而「不得不」做某事,突出客觀性。
I have to go to San Francisco tomorrow on business.
我明天得去舊金山出差。What time do you have to be there?
你得幾點鐘到那兒?Do we have to finish this today?
我們今天必須把這事做完嗎?We'll have to start keeping detailed records.
我們不得不開始作詳盡的記錄。Jackie's ill so they've had to change their plans.
傑基病了,因此他們不得不改變計劃。
must : 通常表示命令或說話人主觀認為必須要做某事,含強調語氣,側重主觀性。
Meat must be cooked thoroughly.
肉必須完全煮熟。I must get some sleep.
我必須睡會兒覺了。You mustn't show this letter to anyone else.
你不許把這封信給其他人看。Luggage must not be left unattended (= it is against the rules).
行李不能無人看管。Must you leave so soon?
你非得走這麼早嗎?"Must I sign this?" "Yes, you must."
「我必須在這上面籤字嗎?」「是的,必須。」