1、用於一般現在時: I go to school every go to the cinema twice a have our meals three times a scentist explores volcano every two weeks.
He jogs twice a day.
他現在一天慢跑一次。
2、用於一般過去時:
He jogged twice a day.
他當時一天慢跑兩次。
3、用於一般將來時:
He will jog twice a day.
4、用於現在完成時:
He has been there twice.