1. must 側重于個人意志和主觀上的必要。have to 側重于客觀上的必要,可用于現(xiàn)在時、過去時和將來時。例如: I know I must study hard. 我知道我必須努力學習。 My brother was very ill, so I had to call the doctor in the mid-night. 我弟弟病得厲害, 我只得半夜里把醫(yī)生請來。 I haven't got any money with me, so I'll have to borrow some from my friend. 我身上沒帶錢,只好向朋友借點了。 He said they must work hard.他說他們必須努力工作。 2. have to可以用于多種時態(tài);而must只用于一般現(xiàn)在或將來。例如: The composition is due to hand in this morning, so I had to finish it last night. 作文今天早晨到期,因此我不得不昨天晚上完成。