2. have to有人称、数、时态的变化, 而must只有一种形式。但must 可 用于间接引语中表示过去的必要 或义务。
He had to look after his sister yesterday.
3. 在否定结构中: don’t have to 表示 “不必”, mustn’t 表示“禁止”。 You don’t have to tell him about it. 你不一定要把此事
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room
1c Pairwork
A: Could you please sweep the floor? B: Yes, sure. / I’m sorry, but I’m
reading the newspaper.
2a Listening and check “yes” or “no”.
have to和must
1. 两词都是 “必须”的意思, have to 表示客观的需要, must 表示 说话人主观上的看法, 既主观 上的必要。
My brother was very ill, so I had to call the doctor in the middle of the night. 我弟弟病得很厉害,我只得半夜里 把医生请来。(客观上需要做这件事) He said that they must work hard. 他说他们必须努力工作。 (主观上要做这件事)
cooking. I _c_a_n_ come later. 2. - _M__u_st_ we clean the windows today?
- No, you _n_e_e_d_n_’_t. You __c_a_nclean them tomorrow.
3. - _M__a_y I watch TV this evening, mum? - No, you _m_u__st_n_’_t. Work _m__u_s_t come first.