a) Were books first printed in
the 15th century?
He asked if books had been first printed in the 15th century.
b) Did printers start printing books in three countries at the same time?
He
asked if printers had started printing books in three countries at the same
time.
c) Can anyone read books on CDs these days?
He wanted to know if anyone could read
books on CDs those days.
d) Did Columbus discover America five centuries ago?
He wondered if Columbus had
discovered America five centuries before.
e) Does the Internet provide us with access to any library all over the world?
He asked if the Internet provided us with access to any library all over the
world.
f) Didn't people living in one part of the world know much about the life of
people in their neighbouring countries not long ago?
He wondered if people living
in one part of the world hadn't known much about the life of people in their
neighbouring countries not long before.