ENIAC, the first modern computer, was created in 1942 at the University of Pennsylvania when the U.S. was involved in World War II; it helped the government store important data but took up a lot of space. Personal computers, introduced in the 1970s, are much smaller and faster than previous computers and allow access to the Internet, which has been around since the 1970s but was not available to most people until the creation of the World Wide Web.

1. Pages 256-257
Exercise 22

2. 1. The abacus, which was created
about 2,000 years ago, helped
people solve arithmetic problems.
Use a non-essential clause for a
collective noun that means all of
those things (like “the computer,”
“the automobile” –all of them in
general).

3. 2. The first modern computer,
which was called ENIAC, took up a
lot of space.
There was only one first modern
computer, so I use a non-essential
clause.

4. 3. ENIAC was created in
1942, when the U.S. was involved
in World War II.
Use a non-essential clause after a
date—there was only one year of
1942.

5. 3. Main sentence: ENIAC was
created in 1942.
Embedded sentence: The U.S. was
involved in World War II in 1942.

ENIAC was created in 1942, when
the U.S was involve din World War
II.

6. 4. ENIAC, which helped the
government store important data,
was built at the University of
Pennsylvania.
Use a non-essential clause after a
name.

7. 5. Personal computers, which were
introduced in the 1970’s, are much
smaller and faster than previous
computers.
Use a non-essential clause because
both the main sentence and the
clause are talking about the same
thing—all personal computers.

8. 6. The Internet, which has been
around since the 1970’s, was not
available to most people until the
World Wide Web was created.