So that 和 in order that 都是用來表示目的，意為「為了；以便；目的在於」，當連接詞用，通常與語氣助動詞 (can、will、could、would 等) 連用。So that 比 in order that 來得常用許多，在非正式情況中，so that 中的 that 往往省略。In order that 是個正式用語，通常用於正式場合。例如：
- John lowered his voice to tell me the secret so that no one would hear. (約翰壓低嗓音告訴我這個秘密，這樣就沒有人能聽到)
- Mary got up early in order that she should/would/might be on time for school. (瑪麗一早就起床以便準時上學)
- I’ll go there so that I can talk to the president. (我要去那裡，這樣我才能跟總統談話)
- In order that you can sign the contract, please give me your address and I will mail it to you. (為了讓你能夠簽約，請給我你的地址，我會把合約寄給你)
- Thomas worked hard so (that) he would earn one million dollars before the age of 25. (湯瑪斯努力工作俾在 25 歲之前能賺到 100 萬)
- I’ve made some sushi so (that) you can have a snack with your girlfriend. (我做了一些壽司，這樣你就能跟你女朋友一起吃點心)
在表示未來時，so that 的後面可以使用現在簡單式或 will/’ll，而 in order that 的後面通常使用現在簡單式。例如：
- I’ll sign and mail the contract so that you get it by Monday. (我今天會簽署並寄出合約，這樣你在週一前就能收到)
= I’ll sign and mail the contract so that you will get it by Monday.
- Monica will leave early in the morning in order that she arrives on time for a stress-management workshop. (莫妮卡明天一大早就要動身，以便準時參加一場壓力管理研討會)
= Monica will leave first thing in the morning so that she arrives on time for a stress-management workshop.
= Monica will leave first thing in the morning so that she’ll arrive on time for a stress-management workshop.
So that 還可表示前因後果 (cause and effect) (但 in order that 則無此用法)，其主要句型為 so … that，意為「如此…以致於；(因為…) 所以」，so 在此當副詞用，後面通常接形容詞或副詞，而 that 有時亦可省略。然而，當 so 的後面沒有接形容詞或副詞時，無論表示目的或因果，兩者都是寫成或說成 so that，此時我們只能從上下文判斷屬於何者。表示因果關係的 so that 省略 that 後，so 就從副詞直接變成連接詞。例如：
- The manager fixed the meeting for 10 so that all employees could come. (經理把會議時間定在 10 點，為的是讓所有員工都能參加) (表目的)
- Gary was so surprised that he remained speechless for a few minutes. (蓋瑞驚訝得好幾分鐘說不出話來) (表因果)
- An almost 50-year-old mom looks so young that people think she’s her son’s girlfriend. (一位近 50 歲的凍齡媽媽看起來是如此的年輕，以致於大家都認為她是她兒子的女朋友) (表因果)
- I was so thirsty I drank up the whole bottle of water. (我很渴，把整瓶水都喝光了) (表因果)
- Everything’s changed so much I can scarcely recognize the place. (一切都變化得如此之大，我幾乎認不出這個地方了) (表因果) － 這兩句都省略了連接詞 that，而 so 還是當副詞用，但可別因此認為這是兩個子句沒有用連接詞連接的 run-on sentence。這是 so … (that) 句型的特色。
- Nothing more was heard from Amy so that we began to wonder if she moved to Japan. (由於再也沒聽到艾美的消息，因此我們便開始懷疑她是否搬到日本了) (表因果)
- These bushes flower in the spring, so that March is a good time to view the booming flowers. (這些灌木春天開花，所以三月是賞花的好時機) (表因果)
- His wife was ill so he did the washing on his very own. (他太太生病了，所以他自己洗衣服) (表因果)
- My blood pressure was getting higher and higher so I quit smoking. (我的血壓越來越高，因此我戒菸了) (表因果) － 這兩句的 so 本身就是連接詞。