1) must用在肯定句中表示较有把握的推测,意为"一定". " X! _5 O' E* o0 H# U3 r( M/ a 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: 1 ~7 P- x. V# S 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)+ g6 J: L+ v# k
He must be working in his office. 他一定在办公室工作呢。8 t1 A8 v4 k. n' K" K- L- x
比较:He must be staying there. 他现在肯定在那里。9 e! h" K- P* Z/ r+ S2 N
He must stay there. 他必须呆在那。 , Z$ U% p) H5 U7 q7 E' u 3) must 表示对已发生的事情的推测时,must 要接完成式。例如:# |* K0 a7 ]& I/ H% c" F
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。7 e; A Z5 D/ s/ {& k- j+ G
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:2 V9 F$ d# K5 G9 A! j) A
——Why didn't you answer my phone call? 为何不接我的电话?' i* T4 P2 I1 a; q6 ?
——Well, I must have been sleeping, so I didn't hear it.唉,肯定在睡觉,所以没有听见。$ s1 A0 |5 R4 p! ?6 S+ v& ]* B
5) 否定推测用can't.例如: ( L$ p& Z5 J. C) j- R/ v! i! S- Z 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。