always, usually, often, sometimes, every day, on Sundays, at weekends, once a week, twice a month, etc.
2、一般过去时:主语+did
基本结构:动词的过去式
常见时间状语:ago, yesterday, the day before yesterday, last week (year, night, month…), in 1986, just now, at the age of 10, at that time, once upon a time, etc.