1,Tom started learning English in 1999
Tom has learned English since 1999
2,How long have you studied English
When did you study English?
3,She has not written to him since last chismast
She last wrote to him last Chrismast
4,I have done this job for 10 years
I began doing this job 10 years ago
5,He last met his classmate last sometime
He has not met his classmate since last sometime