so that的用法

一、引导目的状语从句　so that“以便，为了”，引导一个表示目的的状语从句，此时可与 in order that 换用；从句谓语中常用情态动词 may/might, can/could, should, would 等；主从句间连接紧凑，没有逗号相隔。例：　　My old father began to study computer at the age of sixty so that(= in order that) he might keep up with times. 父亲六十岁时才开始学习电脑，以便跟上时代。　　I spend more time learning English every day so that(= in order that) I can make greater progress this year. 为了今年取得更大进步，我每天用了更多的时间学英语。　　二、引导结果状语从句　　so that“因此，所以”，引导一个表示结果的状语从句，此时不能与 in order that 换用；从句中谓语根据需要使用相应的时态，主从句间可有逗号相隔。本文开头所列举例句中的 so that 就是这种用法。又如：　　She had not planned her time well,so that she did not finish her homework on time. 她没把时间计划好，所以没按时完成家庭作业。　　Wang Lang did not work hard enough, so that she is out of work when she is still young. 王浪工作不够努力，因此，年轻时就失业了。　　三、辨别两种不同状语从句　　1) 根据句子结构辨别　　从句谓语中含有情态动词 may/ might,can/ could, should, would 等，这时 so that 引导的是一个目的状语从句；从句前面有逗号和主句相隔，此时 so that 引导的是一个结果状语从句。试对比以下两个例句：　　Yesterday morning Yang Cheng got up early so that she could catch the first bus. 昨天早上杨成为了赶上早班车起床很早。　　Yesterday morning Yang Cheng got up early, so that she caught the first bus. 昨天早上杨成起床很早，因此，她赶上了早班车。　　2) 根据主从句逻辑关系辨别　　so that 引导目的状语从句，一般表示尚未完成的目的或意图，主句和从句之间是结果与目的关系；而 so that 引导的结果状语从句则是表示主句所导致的结果，主句和从句之间是原因与结果的关系。试比较：　　I tell my students my new telephone number so that they may call me when necessary. 我把新的电话号码告诉学生以便必要时他们给我打个电话。　　I told my students my new telephone number so that all of them called me when necessary. 我把新的电话号码告诉了学生，因此，必要时他们都给我打了电话。　　四、同其它结构转换　　so that 引导目的状语从句时，可以与表目的的动词不定式 (not) to do …/so as(not)to do …/ in order (not) to do … 互换。但主从句主语须一致(句 ① ②)，否则不能转换(句 ③)。　　① We went to the airport so that we might meet Professor Yang there.　→ We went to the airport to meet Professor Yang there.　→ We went to the airport in order to meet Professor Yang there.　→ We went to the airport so as to meet Professor Yang there.　② They had to walk a long way to/ in order to/ so as to fetch some firewood.　→ They had to walk along way so that they might fetch some firewood.　③ Mr.Cheng turned up the recorder so that every student in the classroom could hear clearly. (主从句主语不一致)