1. Overview:
The Present Perfect tense is used to talk about actions or situations that started in the past and continue to the present, or that happened at an unspecified time. "Since" and "for" are used with the Present Perfect to indicate the duration of time.
2. Cases of Usage:
Case 1: Using "since" to indicate a specific starting point in time.
Example: I have lived here since 2010.
Case 2: Using "for" to indicate a duration of time.
Example: I have lived here for ten years.
Case 3: Using "since" and "for" with actions that are still ongoing.
Example: She has worked at the company since she graduated.
Example: They have known each other for five years.
3. Exceptions or Things to Pay Attention To:
"Since" is used only with specific points in time (years, months, days).
Example: I have known him since last week.
"For" is used with periods of time (days, months, years).
Example: I have studied English for two years.
4. Additional Notes:
Common mistakes include mixing up "since" and "for." Remember: "since" refers to a starting point, while "for" refers to the length of time.
