The em dash is perhaps the most versatile punctuation mark. Depending on the context, the em dash can take the place of , , or —in each case to slightly different effect.
This particular word, in many particular circumstances, usually serves no particular purpose. Give particular attention to the particular prospect of cutting it out.
Why should you care? In some style guides, some compound modifiers — especially when that don't end in -ly modify adjectives — are when they appear in the “attributive” position, but not in the “predicate” position. In other words, there's no hyphen if the adjective phrase is what is being predicated. That usually means they should be hyphenated when they come before the noun they modify, but not after, although that's not always the case. For example:
A declarative sentence (or ) is made up of two bits, the subject and the predicate. The subject — usually containing one or more or , along with their accompanying — is who or what does the action of the sentence. The predicate is what's said about the subject: it consists of the main , along with all its modifiers and .
Precision can also mean putting your words in just the right order, or using just the right grammatical construction to make your point. Always read your writing as closely as possible, paying attention to every word, and ask yourself whether every word says exactly what you mean.
Don't confuse am, is, are, to be, and such with the passive voice, and don't confuse with the active voice. The real question is whether the subject of the sentence is doing anything, or having something done to it. I have been carrying is active, while I have been carried is passive.
Quotations marks (“ ”) are a pair of punctuation marks used primarily to mark the beginning and end of a passage attributed to another and repeated word for word. They are also used to indicate meanings and to indicate the unusual or dubious status of a word.
The ellipsis is most commonly represented by three periods (. . . ) although it is occasionally demonstrated with three asterisks (***). The ellipsis is used in writing or printing to indicate an omission, especially of letters or words. Ellipses are frequently used within quotations to jump from one phrase to another, omitting unnecessary words that do not interfere with the meaning. Students writing research papers or newspapers quoting parts of speeches will often employ ellipsis to avoid copying lengthy text that is not needed.
It should be noted that, according to Purdue University, some teachers and editors enlarge the scope of the use of apostrophe, and prefer their use on symbols (&'s), numbers (7's) and capitalized letters (Q&A's), even though they are not necessary.
There's an admirably thorough and precise discussion of the English passive in the blog — worth checking out if you want a better understanding.
Becoming familiar with the basic punctuation marks in the English language will allow you to express yourself better in your writing. Punctuation marks will also make your sentences clearer and more understandable to the reader.
Don't go overboard, though. Some passives are necessary and useful. In scientific writing, for instance, sentences are routinely written in the passive voice; the authors are therefore given less importance, and the facts are made to speak for themselves. Even in non-scientific writing, not all passives can be avoided.
This isn't a comprehensive guide to period usage; that would take more time and energy than I can spare. Besides, you already know most of the rules: a period ends a declarative sentence, and sometimes is used in abbreviations. Still, a few things aren't obvious.
But these are only rough guidelines, not hard-and-fast rules. Different treat words in different ways; they leave a lot uncovered altogether; and they don't address those wacky abbreviations that take other forms (like A/C for air conditioning). Hie thee to the dictionary and, if you're writing for publication, don't be surprised if your editor overrules you.