1 (Helen is in Ireland - she arrived there three days ago) He has been in Ireland for three days.
2 (Jack is here - he arrived on Tuesday) Jack has been here since Tuesday.
3 (It's raining - it started an hour ago) It's been raining for an hour.
4 (I know Sue - I first met her in 2008) I've known Sue since 2008.
5 (Claire and Matt are married - they got married six months ago) Claire and Matt have been married for six months.
6 (Laura is studying medicine at university - she started three years ago) Laura has been studying medicine for three years.
7 (David plays the piano - he started when he was seven years old) David has played the piano since he was seven years old.