目的狀語從句
用法
補充主句中謂語動詞所表示的動作發生的目的，
從句中常含 may, might, can, could, will, would 等情態動詞。
連接詞
in order that, so that, in case, for fear that等
要點
in order that, so that
in order that 比 so that 正式；in order that 引導的從句一般位於句首或者句尾；so that 引導的從句一般位於句尾。
他們引導的從句中常含情態動詞
-例句
In order that we might see the sunrise, we started for the peak early.
為了能看見日出，我們很早就向山頂出發了。
She work hard so that everything would be ready in time.
她努力工作是為了讓一切及時就緒。
in case, for fear that, lest
表示“以防；以免”。
-例句
Leave your key with your neighbor in case you lock yourself out one day.
留把鑰匙給鄰居，以防有一天你把自己鎖在外面。
We all seemed afraid to say what was in our minds, for fear that it should cause trouble.
我們似乎都不敢說出心里的想法，以防萬一引起麻煩。
Take your umbrella wirh you, lest it should rain.
帶上你的傘，以防下雨。
區分：lest 和 for fear that 引導的從句中謂語動詞用 "should + 動詞原形" 表示虛擬
-例句
I am telling you that lest you should make a mistake.
我告訴你那一點，以免你搞錯。
The boy hid himself behind the tree for fear that his father should see.
男孩藏在樹后面，唯恐他的父親發現。
so that, in order that 引導的目的狀語從句與不定式、介詞短語的轉換
1）當從句與主句主語一致時，目的狀從可用 "so as/in order + 不定式（短語）" 代替， so as/ in order 可以省略。
-例句
He ran fast so that he might arrive there before ten o'clock.
-> He ran fast (so as) to arrive there before ten o'clock.
他跑得很快，以便在十點之前到達那里。
He worked day and night in order that he could succeed.
-> He worked day and night (in order) to succeed.
他日夜工作，為了能獲得成功。
2）主從句主語不一致時，目的狀從可換為 "in order for sb. + 不定式（短語）" 的復合結構。
I bought my sister a new dictionary so that she could look up new words conveniently.
-> I bought my sister a new dictionary in order for her to look up new words conveniently.
筆者的話：其實這里還有一個 "so as for" 但是筆者並不能很好地總結出一個東西，而且似乎不常用，就姑且放過。
辨析 so that 引導目的狀從和結果狀從
含義上區別：引導目的狀從表示一種意欲或者可能性，結果狀從表示一種事實。
形式上區別：目的狀從其前不用逗號；結果狀從前面通常有逗號。還有一種方法，可看句中是否有 "can/could, may/might, will/would, should" 等情態動詞，如果沒有，多半是結果狀從。
從語義上分析。
He planned his time well do that he could finish his work on time.
他好好地計划了時間，以便能按時完成工作。（目的狀從）
He didn't plan his time well, so that he did't finish his work on time.
他沒有好好地計划時間，結果沒有按時完成工作。（結果狀從）
