3. 副词类（由副词充当引导词）：immediately, directly, instantly, etc. (一...就...)

4.句型类：no sooner…than…, hardly/scarcely… when…, etc. (一…就…)

e.g. I will give you an answer immediately I finish  my work. The machine will start instantly you press the button.

e.g She had no sooner heard the news than she fainted. No sooner had she heard the news than she fainted. Scarcely had he gone when she appeared.

注意:用于句首时应引起部分倒装, 且前部分一般用过去完成时