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.
Use a non-essential adjective clause
because here is only one Internet.
Also, it is a capitalized proper noun.

9. 7. Berners-Lee, whose name is not
widely recognized, made a great
contribution to the world.
Use a non-essential adjective clause
because it follows a person’s name.

10. 8. Bill Gates went to Harvard
University, where he developed the
programming language BASIC.
Use a non-essential adjective clause
because Harvard University is a
capitalized proper noun.

11. 9. Bill Gates dropped out of
Harvard to work with Paul
Allen, who was his old high school
friend.
Use a non-essential adjective clause
following a person’s name.

12. 10. Together Gates and Allen
founded Microsoft, which has
made both of them very rich.
Use a non-essential adjective clause
because there is only one Microsoft
company, and it is a capitalized
proper noun.

13. 11. In 1984, Apple produced the
first Macintosh computer, which
was easier to use than other
computers.
Use a non-essential adjective clause
because there was only one first
Macintosh computer.

14. 12. In 1984, Bill Gates introduced
Windows, which was Microsoft’s
version of the popular Macintosh
operating system. Use a non-
essential adjective clause because
Windows is a capitalized proper
noun.