Present Perfect with For and Since

For + a period of time

·       for six years, for a week, for a month, for hours, for two hours.

·       I have worked here for five years.

Since + a point in time

• since this morning, since last week, since yesterday,
• since I was a child, since Wednesday, since 2 o'clock.
• I have worked here since 1990.

present perfect with for

• She has lived here for twenty years.
• We have taught at this school for a long time.
• Alice has been married for three months.
• They have been at the hotel for a week.

present perfect with since

• She has lived here since 1980.
• We have taught at this school since 1965
• Alice has been married since March 2nd.
• They have been at the hotel since last Tuesday.

Note:

• For and since can both be used with the past perfect.
• Since can only be used with perfect tenses, for can also be used with the simple past.