The document discusses the use of the present perfect tense with "for" and "since" to indicate periods of time. It explains that "since" is used with a point in time to define the starting point of an action, such as "since Monday". It also explains that "for" is used with a duration of time to define how long an action has been occurring, such as "for a week". Examples are provided to illustrate using the present perfect tense with both "for" and "since".

1. PRESENT PERFECT FOR / SINCE

2. PRESENT PERFECT + for, since Using the present perfect, we can define a period of time before now by considering its starting point , with since + a point in time . Since + a point in time: since this morning, since last week, since yesterday, since I was a child, since Wednesday, since 2 o'clock .

3. SINCE I’ve ridden a bike since I was a child. I’ve ridden a bike since I was 12.

5. Using the present perfect, we can define a period of time before now by considering its duration, with for + a period of time. For + a period of time: for six years, for a week, for a month , for hours, for two hours .

6. FOR They’ve been married for 1 year. They’ve dated for 3 years.

9. I’VE STUDIED ENGLISH SINCE... FOR.... .

12. MD