Which of these is grammatically correct?
1. a) He has been working under my direct supervision since the last two years
1. b) He has been working under my direct supervision for the last two years
2. a) He has not met her since a very long time
2. b) He has not met her in a very long time
Which of the above are correct?
Are all of them correct? My friend says 1.b and 2.b are correct, but I am not sure. Or is this an American English and British English thing? (He mostly goes by American English)