吉光瓊
一般來(lái)說(shuō),英語(yǔ)中可以用于表示“推測(cè)”或“可能性”的情態(tài)動(dòng)詞有can, could, may, might, must。其中must表示主觀推斷的可能性,can表示理論上存在的可能性,may或could表示實(shí)際上存在的可能性,might在表示可能性時(shí)語(yǔ)氣最弱。
must表示推測(cè)時(shí),它的肯定程度比may, might, could大得多,一般只用于肯定句,意為“肯定”“一定會(huì)”“必然”。如:
①You must be very hungry now. Its half past 13.
你一定很餓,現(xiàn)在已經(jīng)下午一點(diǎn)半了。
②Jane must get very bored with her job. She does the same thing every day. 簡(jiǎn)肯定對(duì)她的工作厭煩了,她每天都做同樣的事。
[注]must do(這時(shí)do通常為狀態(tài)動(dòng)詞或系動(dòng)詞),表示對(duì)現(xiàn)在狀態(tài)的推測(cè),如句①和②; must be doing表示對(duì)現(xiàn)在動(dòng)作或狀態(tài)的推測(cè);must have done表示對(duì)過(guò)去的動(dòng)作或狀態(tài)的推測(cè)。
[注]must表示推測(cè)時(shí)通常只用于肯定句,否定句和疑問(wèn)句要用can, could來(lái)代替must。如:
③Hes just had his lunch. He cant be hungry.
他剛吃過(guò)午飯,不會(huì)餓的。
④They have just arrived here. They cant know many people.
他們剛到這里,不可能認(rèn)識(shí)很多人。
can表示推測(cè)時(shí),常用于否定句中表示“不可能”,用于疑問(wèn)句中表示“也許會(huì)/可能……”。用于肯定句中,表示“可能”“有時(shí)會(huì)”。如:
⑤She usually gets up very early. She cant miss the train.
她通常起得很早,不可能誤火車(chē)的。
⑥He cannot be at home. Hes said to have gone to Shanghai.
他不可能在家,據(jù)說(shuō)他去上海了。
[注]在此種用法中,can和could沒(méi)有時(shí)態(tài)的區(qū)別,只是表示可能性的大小,can表示推測(cè)的可能性比could大。
[注]cant have done sth.表示對(duì)過(guò)去行為的推測(cè),意為“不可能做過(guò)某事”“應(yīng)該不會(huì)做過(guò)某事”。
may表示推測(cè)時(shí),可譯為“可能”“也許”,常用于肯定句或否定句中。might表示推測(cè)時(shí)的可能性要比may小,此時(shí)無(wú)時(shí)態(tài)之別,但當(dāng)主句謂語(yǔ)動(dòng)詞為過(guò)去式時(shí),則通常用might。如:
⑦Xiao Yang may/might know his address.
小楊可能/興許知道他的地址。
⑧I may be right or may not be right, but thats what I think.
我可能對(duì),也可能不對(duì),但這是我的想法。
[注]may表示推測(cè)時(shí)一般不用于疑問(wèn)句中,在疑問(wèn)句中通常用can來(lái)代替。如:
⑨Can he be at home? 他可能在家嗎?
⑩Can it be true? 這可能是真的嗎?
[注]在may not表示可能性的句子中,not否定的不是may,而是句中的謂語(yǔ)動(dòng)詞。如:
■You may not see him. 你可能還沒(méi)見(jiàn)過(guò)他。(而不是“你不可能見(jiàn)過(guò)他?!保?/p>
■He may not be there now.
他現(xiàn)在可能不在那兒。(而不是“他不可能在那兒。”)
[注]may/might have done sth.意為“可能/興許已經(jīng)”,表示對(duì)過(guò)去行為的推測(cè),把握性遠(yuǎn)不如must have done sth.。試比較:
■She may/might have read about it in the papers.
她可能/興許已經(jīng)在報(bào)紙上看到這個(gè)消息了。
■She must have read about it in the papers. She asked me many questions about it this morning. 她肯定已經(jīng)在報(bào)紙上看到這個(gè)消息了,今天早上她問(wèn)了我好多有關(guān)這方面的問(wèn)題。
[跟蹤練習(xí)]
根據(jù)句意,從所給選項(xiàng)中選出最佳選項(xiàng)。
1. Helen ____ go on the trip with us but she isnt quite sure yet.
A. may not B. must C. may D. cant
2. ——Isnt that Anns husband over there?
——No, it ____ be him. Im sure he doesnt wear glasses.
A. cant B. must not C. can D. may not
3. ——Someone is knocking at the door.
——Who ____ it be?
A. might B. must C. need D. can
4. ——I just found a video cassette on my desk. Whose cassette is this?
——Oh, that ____ be Johns. Hes been looking for the cassette for an hour. He will be so thankful that you found it.
A. must B. might C. may D. cant
5. ——Is Peter here yet?
——Not yet, but he ____ be here soon. He is usually on time.
A. would B. could C. should D. must
Keys:1.C 2.A 3.D 4.A 5.C