Если речь об одном человеке или 1 предмете или чем-то неисчисляемом (tea, milk, sugar, bread)- тогда has.
my friend (1) has been taught.
My father (1) has been given a new job.
The book (1) has been written
Tea (неисчесл) has been grown here since 19th century.
Если о много - тогда have.
My friends have been taught english.
The books have been written very quickly.
I и you всегда будут употр-ся с have. Это надо выучить.
Hope this will help.