大学英语四级考试涉及的语法知识点多、涉及面宽，对不少考生来说都是一个难题。希望通过本专题的学习，考生能对四级语法有更全面的掌握！
3. 目的状语从句
可以由that，so that，in order that，lest，for fear that，in case等词引导；
lest：以防，从句中的谓语动词必须用should+动词原形；
eg: He wrote the name down for fear that(lest) he should forget it.
He took the umbrella with him lest it should rain.
in case：以防，与lest不同，从句里的时态不做特殊变化；
eg：Take the umbrella with you in case it rains.
for feat that：和lest保持一致；
eg：A variety of activities should be organized so that participants can remain active as long as they want and then go on to something else without feeling guilty and without letting the other participants down.
let…down…：让……感到气馁。