rules concerning grammar, usage, and punctuation.http://www.io.com/~hcexres/textbook/twspell.html

http://www.io.com/~hcexres/textbook/twspell.html

This section covers the most common conventions—or rules—concerning grammar, usage, and punctuation. It also discusses how to handle numbers, abbreviations, and symbols in technical writing. The discussion of the various problems or errors in this section uses the terminology explained in the section on sentence structure and patterns. If any terms, such as object complement or antecedent, are unfamiliar to you, go to that section.

If you have problems with spelling, they may only be a few specific areas that you can overcome once you identify them and practice a bit. The sections in the following review some of the most common areas of spelling problems.
Homonyms

For some writers, their main spelling problem is similar-sounding words, for example, principle and principal or affect and effect. Here is a list of these commonly confused homonyms, with examples of their correct use.
accept, except
The construction form accepted the offer to build the bridge.
Everything has been finished except for the paint job.
advice, advise
The construction firm ignored the engineer's advice.
The engineer advised the firm to use single suspension walkways.
affect, effect
The effect of the increased oil prices has been devastating on
our economy.
The increased oil prices have affected our economy drastically.
cite, site, sight
The consulting engineer cited a paragraph from the building code.
At the construction site, the workers carefully erected the
scaffolding.
The collapse of the walkways was a terrible sight.