Grammatically Correct: The writer's essential guide to punctuation ...

GRAMMAR
It may be necessary to either add or subtract items from this list.
If different words in a sentence take different prepositions, each
preposition must be included. Writers often simply let the preposition
that comes last serve for all, without checking to see if it's
appropriate. In this example, it's not: You can't add somethingjrom
something.
BETTER: It may be necessary to either add items to or subtract them
from this list.
Courses are offered in spring, summer and in fall.
When the same preposition applies to a series of elements, it may
be either repeated for each one or used just once-but you must
be consistent. Don't include it for some items and drop it for others.
BETTER: Courses are offered in spring, in summer and in fall.
OR: Courses are offered in spring, summer and fall.
The more concise version would usually be preferred, but you
may sometimes for reasons of style decide to go with the repetition.
The revised plan called for lower salaries, operating budgets and longer
hours.
The adjective lower is intended to apply to the first two elements,
but fails to connect with the second one because the next element
(hours) takes a different adjective. In fact, the sentence is ambiguous:
if lower is taken to apply only to salaries, a reader could assume
that the plan calls not for a lower operating budget, but for its
creation-that is, that no such budget existed up till now.
BETTER: The revised plan called for lower salaries, lower operating
budgets and longer hours.
OR: The revised plan called for lower salaries and operating budgets, and
longer hours.
Writers who work on a freelance basis don't get steady paychecks, but
one has the advantage of extra tax breaks.
The sentence switches from the plural noun writers to the singular
pronoun one.
BETTER: Writers who work on a freelance basis don't get steady
paychecks, but they have the advantage of extra tax breaks.
OR: As a freelance writer, one doesn't get a steady paycheck, but one
has the advantage of extra tax breaks.
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