1、since作介詞時,后接表示過去時間點的名詞、代詞、動名詞；作連詞時,后接一般過去時的從句；在含有since的句子,謂語動詞用現(xiàn)在完成時.例：Since last seeing you ,I have been ill.
I have been studying English since I was four years old.對since的句子提問用how long.
2、for后跟時間段.例：He has been surfing the Internet for about 3 hours.
3、during后跟時間段.例：During the summer holidays we went swimming every day.
4、in后面跟時間段,并且是表示年,月.例：I won't do back to my home in a year.
5、at后跟時間點,比如六點鐘：at six o'clock.
6、on是指具體到某一天,例：on August 19th在8月19日.