一、It's?important…類
這一類型主要包括It?is?(was)?important?(necessary,?desirable,?imperative,?advisable)that.?.?.句型。如：
It?is?impossible?that?he?should?go?home.?他不可能會回家去。
It?is?necessary?that?I?should?return?it?right?now.?我有必要馬上把它還回去。
It?is?important?that?we?should?speah?politely.?我們說話要有禮貌，這是很重要的。
It?is?not?necessary?that?everyone?be?a?scientist.?沒有必要使每一個人都成為科學家。
It?is?imperative?that?we?should?practise?critidsm?and?self-criticism.?應當進行批評與自我批評。
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二、It's?a?pity…類
It?is?a?pity?that?she?should?fare?so?badly.?她竟吃得這么差，真可憐。
It's?a?pity?that?he?should?be?so?obstinate.?真遺憾他竟這樣倔犟。
It?was?a?pity?that?you?couldn't?come.?你不能來，真是太遺憾了。
It?is?a?pity?that?she?failed?the?driving?examination.?她沒通過駕駛考試真是遺憾。
It?is?his?desire?that?a?medical?man?should?stay?here.?他希望有一個醫(yī)務人員留在這里。
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三、It's?desired…類
這種主語從句還常用在It?is?(was)?desired?(suggested,?settled,?proposed,?requested,?decided,?etc.?)?that...句型。如：
It?is?requested?that?a?vote?be?taken.?建議付諸表決。
It?is?settled?that?you?leave?us,?then??那么你肯定要離開我們羅?
It?was?proposed?that?this?matter?be?considered?at?the?next?meeting.?有人提議這事下次會議再討論。
It?is?desired?that?this?rule?should?be?brought?to?the?attention?of?the?staff.?希望這條規(guī)則引起全體職員的注意。
注意：
(1)?在現(xiàn)代英語中，有時也可不用虛擬語氣而用陳述語氣，但初學者宜慎用。
(2)?在It?is?amazing?(strange,?surprising,?astonishing,?a?pity,?a?shame)以及?I?am?surprised?(sorry)?和I?regret等結構后的that?從句中有時也用should，表示說話人的驚異、懊悔、失望等情感，常含有“竟然”之意：
It's?strange?that?he?should?be?so?rude.?他竟如此無禮，真是奇怪。
I'm?surprised?that?he?should?have?failed.?他竟然失敗了，這使我很吃驚。
若不用虛擬語氣也可以，則不帶感情?色彩，比較：
It's?a?pity?that?he?failed?the?exam.?他考試沒及格，真是遺憾。
It's?a?pity?that?he?should?have?failed?the?exam.?他考試竟沒及格，真是遺憾。