虚拟语气用于状语从句

　　1、在for fear that,in case,lest引导的从句中，若用虚拟语气时，从句谓语为：(should) + do。并且should能省略(for fear that，lest)，in case不能省略

　　She examined the door again for fear that a thief (should) come in.

　　她又把门检查了一遍，以防盗贼的进入。

　　He started out earlier lest he (should) be late.

　　他早早地就出发了以防迟到。

　　2、在so that / in order that 所引导的目的状语从句中，从句中的谓语为：can / could / may / might / will / would / should + do。

　　He goes closer to the speaker so that he can hear him clearer. 他走近说话的人以便能听得更清楚。

　　He read the letter carefully in order that he should not miss a word. 他把信读得很仔细以便不漏掉一个字。