USE 1 Unspecified Time Before Now
We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc.
- There have been many earthquakes in California.
- People have traveled to the Moon.
USE 2 Change Over Time
We often use the Present Perfect to talk about change that has happened over a period of time. Examples:
- You have grown since the last time I saw you.
- The government has become more interested in arts education.
USE 3 Accomplishments
We often use the Present Perfect to list the accomplishments of individuals and humanity. You cannot mention a specific time.
Examples:
- Man has walked on the Moon.
- Our son has learned how to read.
- Doctors have cured many deadly diseases.
USE 4 Duration From the Past Until Now
We use the Present Perfect to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect.
Examples:
- I have had a cold for two weeks.
- She has been in England for six months.
- Mary has loved chocolate since she was a little girl.
