2009年12月大學(xué)英語(yǔ)四六級(jí)考試語(yǔ)法精要(五)

　　12. It is (about/high) time (that) 句型

　　該句型表示“(早)該做…”，其后的定語(yǔ)從句中的謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣表示。在測(cè)試中從句的謂語(yǔ)動(dòng)詞用一般過(guò)去時(shí)。

　　It is time that we went to bed.

　　It is high time that somebody taught you to behave yourself.

　　13. 表示猜測(cè)的幾種不同的方法及意義

　　一些情態(tài)動(dòng)詞與動(dòng)詞的完成式連用能夠表示對(duì)過(guò)去情況的猜測(cè)或者未實(shí)現(xiàn)的可能性。

　　1) could have + 過(guò)去分詞

　　A. 表示對(duì)過(guò)去可能發(fā)生的事情的推測(cè)，意為，“可能做了某事”。

　　He couldn’t have seen her yesterday.

　　They could have lost their way.

　　B. 表示某事在過(guò)去本有可能發(fā)生，但事實(shí)上并未發(fā)生，意為，“本可以做某事”。

　　We could have started a little earlier.

　　I could have killed her. It was a narrow escape.

　　2) may (might) have + 過(guò)去分詞

　　A. 表示對(duì)過(guò)去情況的推測(cè)，意為，“可能已做某事”。

　　He may have heard the news.

　　I might have come to a wrong conclusion.

　　B. 表示一種未實(shí)現(xiàn)的可能性，即本可以做某事，而實(shí)際上并沒(méi)有做，有時(shí)含有抱怨的口吻。

　　It was a narrow escape. You might have killed yourself.

　　A lot of men died who might have been saved.

　　3) must have + 過(guò)去分詞

　　表示邏輯上的必然性，即按照某些現(xiàn)象推斷過(guò)去肯定發(fā)生過(guò)的某事。

　　She must have made a big mistake.

　　The city at one time must have been prosperous, for it enjoyed a high level of civilization.