From the collection Written Proficiency Comments, by A. Kostia
You cannot write an essay
just by taking sentences
from other sources and replacing
one or two words in them. Sources
are for information, not for
copying sentences from. Write your own
text. Use your own
words. Write about why you believe
these inventions are so significant. Focus
on their role rather than on
random facts about their history.
This should be your own
essay, not a rehash
of a Wikipedia entry.