I demand/insist that ...
結構︰主詞1+意志動詞(demand/insist 等)+(that)+主詞2+(should)+原形動詞
說明︰意志<動詞>有四類：建議(suggest，recommend，propose，advise，urge 等)，要求(desire， ask，demand，require，request，maintain，insist 等)，命令(order，command 等)，規定( rule，regulate，stipulate 等)。其後接 that-<子句>時，該<子句>裡的<動詞>要用原形或“should+<動詞>”。美式英語通常省略 should。
The committee moved that the meeting (should) be adjourned. 委員提議休會。
His parents demanded that he (should) be back by ten. 他的父母要求他十點以前回家。
The employees demand that their salaries be raised. 員工們要求加薪。
They ruled that the law (should) not be imposed. 他們規定不應加重法律。
His father ordered that he (should) keep a diary in English.
他的父親規定他要用英文寫日記。
My mother encouraged me and insisted that I continue my education.
我媽媽鼓勵我，而且堅持我應該繼續我的教育。
He insisted that I (should) apologize to her. 他堅持我應該向她道歉。
Recently, many states have insisted that high schools teach students how to drive.
最近，許多州堅持中學應該教學生如何開車。
His father insisted that they (should) move to the country. 他爸爸堅持他們應該搬到鄉下。

It is proper ... that ...
結構︰It is+意志形容詞(important 等)+(that)+主詞+(should)+原形動詞
說明︰意志<形容詞>包括 important，necessary，imperative，essential，urgent，desirable， advisable，recommendable，proper 等。that-<子句>中只能用<助動詞> 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.
他有必要整理些資料供我參考。
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.
急需將食物和衣服送給災民。
It is desirable that we (should) provide for the poor at Christmas.
在聖誕節施捨窮人是可喜的事。
It is important that he be quiet. 他該保持安靜是有必要的。
It is important that he not do it. 他不該做那事是有必要的。
It is requested that all members be present at the party. 全體會員都被要求出席這次晚會。
It is proper that such a bad man be punished severely. 這麼壞的人受重罰是應該的。

Imperative Sentence + Conj. + Main Clause
結構︰祈使句+連接詞+主句
說明︰<祈使句>表示須具備的條件，主句表示可能的結果。<祈使句>代替 if 子句進行評說，提出要求，訂立協議，提供建議或威脅等。<祈使句>的用法比 if 子句表示的更為緊迫。
Provide the materials and we’ll do the job. 提供材料，我們就做這活。
Stop shouting or you’ll wake up the neighbors. 不要喊了，否則你會把鄰居吵醒的。
Put that down or else I’ll smack you. 把它放下，不然我就揍你。
Be there on time, otherwise you’ll create a bad impression.
要準時來，否則你會給人一個壞的印象。
Fail to pay and they’ll cut off the electricity. 你(如果)不付款，他們就要斷電。
Stop eating sweets, or you won’t get any dinner. 你如果不停止吃糖，你就不要吃飯。

Unless ...
結構︰Unless+子句，主要子句
說明︰此句型意為“除非…”。unless 引導一個否定假設句，相當於 if ... not ...，有時可以互換使用。總體上看，unless 的語氣強於 if ... not ...，而且有時較為常用，例如在最後通牒中。
Unless you change your mind (=If you don’t change you mind), I won’t be able to help you.
除非你改變你的想法，否則我不能幫助你。
Unless the management improves their offer, there’ll be a strike.
除非資方做出進一步的建議，否則將舉行罷工。
I couldn’t have got to the meeting on time - unless I had caught an earlier train.
我不可能及時趕到會場，除非我趕上了較找的一班火車。

Provided/Providing (that) ....
結構︰Provided/provided(that)+子句，S+V ...
說明︰此句型意為“如果…”。Provided/Providing (that) 引導假設條件句，其功能相當於 if。
Provided/Providing (that) you clear your desk by this evening, you can have tomorrow off.
如果你到今晚把手頭上的工作做完，你明天就可以休息。

As/So long as ...
結構︰As/So long as +子句，S+V ...
說明︰此句型意為“如果…，只要…”。As/So long as引導一個條件假設句，其功能相當於 if。
So (As) long as you clear your desk by this evening, you can have tomorrow leave.
如果你到今晚把手頭上的工作做完，你明天就可以休息。
As long as you drive carefully, you will be very safe. 如果你開車小心，你就會很安全。
You may eat anything, so long as you don’t eat too much.
只要不吃得太多，你可以吃任何東西。
As long as live, I will help you. 只要我活著，我都會幫助你。
As long as you don’t betray me, I’ll do whatever you ask me to (do).
只要你不出賣我，要我做什麼我都願意。
We’ll ship the goods at an early time as long as there is a steamer.只要有船，我們就盡早裝貨。
You will never be good students so long as you goof around.
如果你們成天游手好閒，就永遠也成不了好學生。