If it were not for ……

　　结构︰if it were not for+名词/子句，主词+would/should 等+原形动词…

　　说明︰此句型意为“若非（有）…”。此类句构专门用于表示与现在事实相反的。亦可用“but for+”或“without+”代替。were 可以提前，省略 if，如例句3.

　　If it were not for his presence， I would punish you. 要不是他在场，我会处罚你的。

　　But for your advice， I should have failed. 要不是你的忠告，我会失败的。

　　But for music （=Were it not for music）， life would be dull. 要不是音乐，人生会很无聊。

　　If it were not for oxygen and nitrogen in the air， no man could live on the earth.

　　大气中如果没有氧和氮，人就无法生存于地球了。

　　Without air， all living things would die. 若非空气，所有的生物都会死亡。

　　Without newspaper， we would get behind the times. 要不是报纸，我们都赶不上时代了。

　　I should be lonely， were it not for the birds and the flowers. 我会寂寞，若非有鸟也有花。

　　Were it not for his help， I could not finish the work.若非有他的帮助，我就不能完成这件工作。

　　Were it not for science， we could not live a comfortable live.

　　若非科学，我们无法过着舒适的生活。

　　If it had not been for ……

　　结构︰if it had not been for+名词/子句，主词+would/should 等+原形动词…

　　说明︰此句型意为“若非（有）…”。此类句构专门用于表示与过去事实相反的。

　　If it had not been for his help， I should have failed. 如果没有他的帮忙，我应该已经失败。

　　Had it not been for your timely help， our company would have been on the verge of bankruptcy. 若非你及时伸出援助之手，本公司将会濒临破产的边缘。

　　If it had not been for these experiments， the improvement of the machine would have been impossible. 要不是这些实验，这部机器也许就不可能改良了。

　　Had it not been for the kind guide， I might have got lost in the mountains.

　　要不是这位好心的向导，我可能就在山中迷路了。

　　If it had not been that he was here， I would have punished you.

　　要不是他在场，我当时就会处罚你。

　　I demand/insist that ……

　　结构︰主词1+意志动词（demand/insist 等）+（that）+主词2+（should）+原形动词

　　说明︰意志有四类：建议（suggest，recommend，propose，advise，urge 等），要求（desire， ask，demand，require，request，maintain，insist 等），命令（order，command 等），规定（ rule，regulate，stipulate 等）其后接 that-时，该里的要用原形或“should+”。美式英语通常省略 should.

　　The committee moved that the meeting （should） be adjourned. 委员提议休会。

　　His parents demanded that he （should） be back by ten. 他的父母要求他十点以前回家。

　　The employees demand that their salaries be raised. 员工们要求加薪。

　　They ruled that the law （should） not be imposed. 他们规定不应加重法律。

　　His father ordered that he （should） keep a diary in English.

　　他的父亲规定他要用英文写日记。

　　My mother encouraged me and insisted that I continue my education.

　　我妈妈鼓励我，而且坚持我应该继续我的教育。

　　He insisted that I （should） apologize to her. 他坚持我应该向她道歉。

　　Recently， many states have insisted that high schools teach students how to drive.

　　最近，许多州坚持中学应该教学生如何开车。

　　His father insisted that they （should） move to the country. 他爸爸坚持他们应该搬到乡下。

　　It is proper …… that ……

　　结构︰It is+意志形容词（important 等）+（that）+主词+（should）+原形动词

　　说明︰意志包括 important，necessary，imperative，essential，urgent，desirable， advisable，recommendable，proper 等。that-中只能用 should，不可用 must，而 should 往往予以省略。

　　It is necessary that he （should） sort out the information for my reference.

　　他有必要整理些资料供我参考。

　　It is essential that he get up early. 他有必要早起。

　　It is urgent that food and clothing （should） be sent to the sufferers.

　　急需将食物和衣服送给灾民。

　　It is desirable that we （should） provide for the poor at Christmas.

　　在圣诞节施舍穷人是可喜的事。

　　It is important that he be quiet. 他该保持安静是有必要的。

　　It is important that he not do it. 他不该做那事是有必要的。

　　It is requested that all members be present at the party. 全体会员都被要求出席这次晚会。

　　It is proper that such a bad man be punished severely. 这么坏的人受重罚是应该的。

　　Imperative Sentence + Conj. + Main Clause