Present: I read a book
and
Present Progressive: I am reading a book
are both
я читаю книгу
in Russian, but how would you translate something like the past progressive, as in 'They were going to go shopping' or the past perfect progressive as in, 'They had been shopping for a long time'?
Also, if you have 'у меня книга' for 'I have a book' how do you express possession in the future tense, as in, 'I will have a book'?
Any help would be great!