目的状语从句
说明动作的目的，常用 so that、in order that 引导。
so that / in order that + 从句（常含 can / could / may / might）
要点
- so that、in order that 引导目的状语从句，从句里常带情态动词。
- so as to / in order to 后面接动词原形，是简化形式。
- 目的状语从句放在主句前后都可以。
- 与结果状语从句的区别：目的从句表「为了」，常含 can / could。
- for fear that / in case 表"免得、以防"，方向与 so that 相反 —— 目的这一族里只有它们说的是"不希望发生的那件事"。
- to do 表目的时，它的逻辑主语必须就是主句主语：To save time, we took a taxi. 说得通；To save time, a taxi was called. 就挂了 —— 主语对不上要改回从句。
- 否定目的说 so as not to / so that … not：She left early so as not to be seen. —— not 排在 to 前面，不写成 so to not。
- "好让"还能缩成 let：Turn down the TV so that the baby can sleep. ＝ Turn down the TV to let the baby sleep. —— let 那一式短，但后面只接动词，不接一整句。
例句
He got up early so that he could catch the first bus.
他起得很早，为了赶上头班车。
She studies hard in order that she can pass the exam.
她努力学习，为了能通过考试。
We took a taxi in order to save time.
我们打车是为了省时间。
Turn down the TV so that the baby can sleep.
把电视声音调小些，好让宝宝睡觉。
Write the number down in case you forget it.
把号码写下来，免得忘。
He lowered his voice so that nobody should hear him.
他把声音压低，免得被人听见。
易错提示
- 目的从句里几乎总有 can / could / may / might，看到它们多半是目的。
- so that 前面没有逗号多半是目的，前面有逗号多半是结果。
- lest（以免、唯恐，极书面）后面接 should + 原形或裸原形：He spoke slowly lest anyone should misunderstand. —— 认得出就够，不必自己在口语里用。
- so that 与 such … that 分家：前者是目的或结果，后者表程度（如此…以致），且 such 后面必须有名词 —— 那一路住在「结果状语从句」那条。