Since and for is commonly associated to perfect continuous tenses. As explained in the previous chapter of perfect continuous the verbal action has undergone two main functions;
- the continuity for certain time.
- completion after that.
The difference between continuous and perfect continuous
- Continuous tenses show only continuity of verbal action.
- Perfect continuous tenses show continuity of verbal action for certain time.
- Continuous: They are jogging.
- Perfect continuous: They have been jogging.
In case of the first sentence the action of jogging is continuous whereas in the second sentence it has been continuous for certain time, and if we use since or for it will be further clear e.g. "They have been jogging for an hour."
Any action that has been continuous for certain time implies two things; either we have to say for how long it has been continued or when it has been started. It is here that we need since and for.
- [since] is used for point of time whereas [for] for period of time which is further explained below.
Point on time means the certain time when verbal action was started. So whenever in perfect continuous tenses we have to talk about the time the verbal action started from we have to use since. There are different types of point of time as follows;
- Any certain time: e.g. since 2 o'clock, since 4:30 etc.
Example: I have been waiting for him since 2 o 'clock.
- Days: since Tuesday, since Monday etc.
Example: He hasn 't been feeling well since Monday.
- Season: since last summer, since winter etc.
Example: We have been attending English class since last summer.
- Any event: since he died, since winter vacations etc.
Example: Max hasn 't been enjoying his life since his wife passed away.
- Year: since 2010, since 1950 etc.
Example: Joe has been teaching in this college since 2002.
- Months: since January, since June etc.
Example: He has been receiving pension since January.
- Age: since I was five, since he was sixteen etc.
Example: His daughter has been studying in Oxford school since she was ten.
For is used for period of time. It means when we talk about the duration of verbal action, like; two months, four hours, three years, five centuries etc. There are different types of period of time, like; moments, years, months, centuries etc.
- I have been waiting for him for two hours.
- She has been reading newspaper for 20 minutes.
- Players have been jogging for one hour.
Sometimes since and for are used in one sentence where we show both duration and starting time for the verbal action.
Since and for in one sentence
- I have been writing articles in the newspaper for two years since I settled in this city.
Sometimes one word may stand for both point and period of time. In such cases we have to see what is more likely in accordance with the context.
- I have been dreaming for good days since long. (long here is point of time)
- I have been dreaming for good days for long. (long here is the period of time)
Position of since and for in a sentence
Position of since and for in a sentence may vary. They can be either at the start or at the end of the sentence, like;
- I have been missing you since long.
- Since long I have been missing you.