19.4 目的状语从句
 
  表示目的状语的从句可以由that, so that, in order that, lest, for fear that, in case等词引导,例如:
   You must speak louder so that /in order that you can be heard by all.
   He wrote the name down for fear that(lest) he should forget it.
   Better take more clothes in case the weather is cold.