如：The students were busy taking notes while they were listening to the lecture. The young mostly enjoy pop music while the old usually prefer classical. While there exists much unemployment in almost all cities， people with special skills are still in great demand.
注意：while 表示“尽管”时，相当于although / though / as，但while / although引导的让步状语从句不用倒装语序，though引导的状语从句可以倒装也可以不倒装，而as引导的状语从句则必须倒装。
如：Though the bride is happy / Happy though the bride is， she will feel homesick at the beginning. Happy as the bride is， she will feel homesick at the beginning.
1. until / till从句或短语与肯定的主句连用时，主句的谓语必须是延续性动词，表示主句的动作一直持续到until / till所表示的时间为止。
如：You may stay here until the rain stops. Mr. Bush remained there till his brother arrived.
2. until / till从句或短语与否定的主句连用时，主句的谓语必须是非延续性动词，表示“直到……才”，即主句的动作到until / till所表示的时间才开始。
如：David won‘t go to bed until / till his wife returns. Leo didn’t come until he had gone over his lesson.
3. not until ......位于句首时，主句须用倒装语序。
如：Not until I began to work did I realize how much time I had wasted.
4. not until …… 结构可用于强调句中。
如：It was not until she came to see us that we knew her mother was ill in bed.
三、so that so that可以引导目的状语从句与结果状语从句。
如：If you do know， answer in a loud enough voice so that all the class may hear. （目的状语从句）
It rained hard the day before yesterday， so that we had to stay at home. （结果状语从句）
2. 当从句之前的so that可用in order that代替时，为目的状语从句；反之，为结果状语从句。
如：We now study hard so that we may work well in the future. （= We now study hard in order that we may work well in the future.） （目的状语从句）