(一)情態(tài)動詞
一。情態(tài)動詞的現(xiàn)在完成式的用法
情態(tài)動詞現(xiàn)在完成式主要有兩個功能：表示已經(jīng)發(fā)生的情況和表示虛擬語氣。在這兩個方面must/mustn't，;can/cann't;need/needn't;may/mayn't;might/mightn't;should/shouldn't;
ougtht等情態(tài)動詞+完成式表示的意思是有一定區(qū)別的
1.表示已經(jīng)發(fā)生的情況。
1)must have+過去分詞，表示對已發(fā)生情況的肯定推測，譯為“(昨天)一定……”。如：
My pain apparent the moment I walked into the room， for the first man I met asked sympathetically：“ Are you feeling all right?”
[A] must be [B] had been [C] must have been [D] had to be
(答案為C)
2)can't / couldn't have+過去分詞，表示對已發(fā)生情況的否定推測，譯為“(昨天)一定沒……”。如：
Mary my letter; otherwise she would have replied before now.
[A] couldn't have received [B] ought to have received
[C] has received [D] shouldn't have received
(答案為A)
3)may / might have +過去分詞，表示對已發(fā)生的事情做不肯定、可能性很小的推測，或事實上根本沒發(fā)生，譯為“也許……”。如：
At Florida Power's Crystal River plant， a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician.
2.表示虛擬語氣。
1) needn't have + 過去分詞，表示做了不必做的事，相當于“didn't need to do”，譯為“其實沒必要……”。如：
You needn't have come over yourself.
As it turned out to be a small house party， we so formally.
[A] needn't dress up [B]did not need have dressed up
[C] did not need dress up [D] needn't have dressed up
(沒有必要穿的那么正式，體現(xiàn)是說話者的建議，實際結(jié)果是否真的穿的很正式?jīng)]有確定，答案為D)
2)should have +過去分詞，表示應該做某事但實際上未做，譯為“本應該……”should not + have過去分詞表示本不應該做某事但實際上做了，譯為“本不應該……”。如：
I regret having left the work unfinished; I should have planned everything ahead carefully.
我本來應該事先認真地把每件事情規(guī)劃的很好，但實際上作者還是沒有規(guī)劃好，以至工作沒有完成。
3) ought to have +過去分詞，表示動作按理該發(fā)生了，但實際上未發(fā)生，譯為“該……”，與should 的完成式含義類似。如：
The porter ought to have called the fire-brigade as soon as he saw the fire in the stock， which went up in smoke .
4) could have +過去分詞，表示過去本來可以做但卻未做，譯為“完全可以……”。這點與ought/should/ have +過去分詞用法相似。如：
What you said is right， but you could have phrased it more tactfully.
5) may/ might have +過去分詞，表示過去可以做但實際未做，譯為“(那樣)也許會……”。如：
所屬頻道：英語
責任編輯：阮老師
