the difference in meaning.
1 a He's written a book.
b He's been writing a book.
2 a Who's eaten my chocolates?
b Who's been eating my chocolates
3 a She's never been to a wedding before,
b She'd never been to a wedding before
b I've been trying to call
5 a They been married for thirty-twe years!
b. They ve been married for thirty-five years!