so as to/so...as to

so as to 总是连在一起,后面紧跟动词不定式,它在意义上相当于 in order to(后者更正式一些)。它所引导的动词不定式往往起目的状语的作用,因此,把 so as 省略掉之后,动词不定式的意义常常保持不变。例如:

1. Students should take notes (so as) to make revision easier. (CGEL) 学生应当记笔记，以便容易复习。

2. We started early so as to get there before ten. 我们很早就动身了,以便10点前到达那里。

3. Turn the volume down so as not to wake the baby. (CGEL) 把音量调小一些,免得把婴儿吵醒。

4. The test questions are kept secret, so as to prevent cheating. (LDCE) 试题应保密，以免作弊。

5. Then Columbus took the egg and struck its small end gently upon the table so as to break the shell a little. (许国璋《英语》第二册) 哥伦布拿起鸡蛋, 把它的小头轻轻往桌子上一敲, 把蛋壳打碎了一点。

但是, so as to 有时也起结果状语的作用:

1. The moon was bright, so as to enable them to find a way through the forest. 月光很明亮，使得他们找到了穿过森林的路。

2. He took back the letter and the photograph and tucked them inside the pouch around his neck, so as not to have to look at her and give himself away. (J. K. Rowling, Harry Potter and the Deathly Hallows) 他把信和照片重新塞进口袋里，因此可以不用盯着赫敏，也不会泄漏自己的心事。（《哈利·波特与死亡圣徒》）

so...as to 结构中, so 总是与 as to 分开用。在 so 之后可加入形容词或副词。as to 所引导的动词不定式往往起结果状语的作用。这一结构在语义上相当于 so + 形容词或副词 + that 从句。例如：

1. Who could be so mean as to do a thing like that? (DAI) 是谁这样卑鄙竟然做出这样的事情来?

2. Are you so naive as to imagine this is not taking place elsewhere? (Mis) 你是不是那么天真竟然认为这事不会在其他地方发生？

3. Some really keen enthusiasts go so far as to build their own record players and radio transmitters. (New Concept English, Book 3, L.46) 某些确实热衷于此道的人甚至自己安装电唱机或发报机。

偶尔, so ... as to 也用来表示目的:

I rose so early as to be in time for the departure. 我起得很早以便能及时启程。