E-books E-books (1) ... (2) ... a few decades but
recently they (3) ... more popular with
readers. The first e-books (4) ... technical
manuals or specialized documents that only
a few people (5) ... interested in. In recent
years, novelists (6) ... their books online and
the contents of some of the best libraries
in the world are now in cyber archives. A
few years (7) companies like Sony and
Amazon (8) ... e-readers to make it easier for
people to read e-books.
1 a) existed
b) have existed
c) has existed
2 a) ago
b) for
c) since
3 a) have become
b) have became
c) became
4 a) was
b) have been
c) were
5 a) was
b) have been
c) were
6 a) published
b) have published
c) has published
7 a) just
b) since
c) ago
8 a) invented
b) have invented
c) have invent​