1) must用在肯定句中表示较有把握的推测,意为"一定"./ x5 b2 f9 ?7 ~& h/ J+ P9 V6 A5 n
2) must表对现在的状态或现在正发生的事情的推测时,must 后面通常接系动词be 的原形或行为动词的进行式。例如: + y7 @- c+ m8 _7 W6 P You have worked hard all day. You must be tired. 你辛苦干一整天,一定累了。(对现在情况的推测判断)$ H' R8 {4 u0 I' e- o$ P! m
He must be working in his office. 他一定在办公室工作呢。2 @$ k% [7 P# w4 B1 c; D
比较:He must be staying there. 他现在肯定在那里。 0 Z% ]" }. m3 R8 c. T$ i He must stay there. 他必须呆在那。. J; H @9 t6 ^- u. G2 `0 @' t' g
3) must 表示对已发生的事情的推测时,must 要接完成式。例如:6 o( u! c0 B3 Y
I didn't hear the phone. I must have been asleep. 我刚才没有听到电话,我想必是睡着了。3 M+ y4 o! b5 Q1 E# ^3 n% S* D$ `: @
4) must表示对过去某时正发生的事情的推测,must 后面要接不定式的完成进行式。例如:5 x& d" R+ h: V* h0 x
——Why didn't you answer my phone call? 为何不接我的电话? & ^" l8 y% M+ y% `" K/ R ——Well, I must have been sleeping, so I didn't hear it.唉,肯定在睡觉,所以没有听见。3 g- M- r& u- m; x4 s1 X
5) 否定推测用can't.例如: $ F& e! V! A/ H3 \. W% c If Tom didn't leave here until five o'clock, he can't be home yet. 如果汤姆五点才离开这儿,他此时一定还未到家。