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Extensions can take many forms.
These are the most common types of extensions.
The original definition is included in brackets followed by the extension.
Further definition, use further definition when you need to define terms you
used in your original definition.
>> In water softening, zeolite is an exchange resin that releases sodium ions
while gaining calcium and magnesium ions.
Zeolite is a collection of small polystyrene beads that forms a resin
carrying a negative charge.
>> Comparison and contrast, use comparison and
contrast when you need to show differences or similarities.
>> In water softening, zeolite is an exchange resin that releases sodium
ions while gaining calcium and magnesium ions.
Zeolite collects calcium and
magnesium ions in the same way a feather broom collects dust.
>> Classification,
use classification when you need to organize information into categories.
>> In water softening, zeolite is an exchange resin that releases sodium
ions while gaining calcium and magnesium ions.
Zeolite is used for ion-exchange home water softening, while lime and
soda ash are used in precipitating municipal water softeners.
>> Cause and effect, use cause and effect when you need to demonstrate
why something happens or when you need to trace results.
>> In water softening, zeolite is exchange resin
that releases sodium ions while gaining calcium and magnesium ions.
Zeolite carries a negative charge and
attracts the positively charged calcium and magnesium ions in water.
>> Process, use process when you need to list the steps of a procedure.
>> In water softening, zeolite is an exchange resin that releases
sodium ions while gaining calcium and magnesium ions.
First, the zeolite is charged with sodium ions from a salt brine solution in
the regeneration step.
Once charged, the zeolite absorbs calcium and magnesium ions from passing
hard water while releasing sodium ions into the resulting soft water.
>> Exemplification, use exemplification when you need to give real or
analogous examples.
>> In water softening, zeolite is an exchange resin that releases sodium ions
while gaining calcium and magnesium ions.
Examples of the zeolite group include analcimes, chabazites, and gismondines.
>> Etymology, use etymology to show the linguistic genesis of the term.
>> In water softening, zeolite is an exchange resin that releases
sodium ions while gaining calcium and magnesium ions.
The term zeolite comes from the Greek words zeon, meaning to boil,
and lithos, meaning stone.
It was first coined by the Swedish mineralogist Alex Fredrick Cronstedt in
the 18th century.
>> In some situations you may need to sacrifice desired precision in your
definition to achieve the desired level of communication.
At times, for example, it is not a good idea to try to
achieve expert level precision with an uninformed audience.
Consider the following two definitions of a black hole,
the astrophysical phenomenon that is supposed to exist somewhere in space.
Definition 1.
>> In astrophysics, a black hole is a set of events from which it
wasn't possible to escape to a large distance.
A black hole gets its name from its boundary, called an event horizon,
which is formed by the paths in space-time of rays of light that just fail to get
away, hovering instead forever on the edge.
And, consequently, moving path parallel to and away from one another.
>> Definition 2.
>> In astrophysics, a black hole is a collapsed neutron star whose gravity is so
great that even light can't escape.
Although fusion reactions within this collapsed star still may emit brilliant
rays of light, when it is viewed from the outside,
the black hole appears to be a totally dark void in space.
>> Definition 1 functions at the expert level.
For theoretical physicists, it provides a precise and
accurate description of a black hole, and thus is appropriate for their needs.
But for the less informed reader, it represents a mind twisting experience
that in many cases can leave readers more confused about the term,
than they were before they read it.
Definition 2 functions at the level of the average reader.
It is not nearly as precise or accurate as the first definition, but
it communicates the basic gist of what constitutes a black hole in space.
The problem is that, to be precisely correct and absolutely accurate,
you would have to function at a level where you cannot
effectively communicate with the average reader.
If you were writing for average reader, you would have to make a decision here.
Either be absolutely correct and communicate less effectively, or
be less than absolutely correct and communicate more effectively.
Since your goal is effective communication, your decision is obvious.
Elena BazanovaDirector of the Language Training and Testing Center
