Summary: Learn to properly use who and whom, that or which, affect and effect with these excellent online resources and the various tricks and tips that they (and I) provide today.
There are many tricks and tips that you can use to help remember the various—and often contradictory—rules of English grammar. On Monday, I spelled out the subtle differences between the words assume and presume (and reminded you that presumption often takes some basis of logic into consideration, while strictly assuming, or guessing, makes an a-s-s out of u and me).
Here are a few other mnemonics that can help you remember the rules:
Who vs. whom – If you know when to use he and when to use him in a sentence, then you can properly use who and whom. "To whom did you give the money?" "I gave it to him." "Who's at the door?" "He's at the door." Visit GrammarBook.com for more examples of this rule.
That vs. which – Is the information you're about to share important? That's when you want to use that! If it's not such a big deal, you can separate it with commas and call it a which. Some writers and editors refer to these parts of a sentence as essential clauses and unessential clauses, or restrictive clauses and non-restrictive clauses. Want more help? Go to Grammar Girl's Quick and Dirty Tips and see why "the sentence that you're writing, which includes some extra information, contains both clause types—no matter what you call them." Always remember to share that important info. up-front and denote other info., which may be less important, with commas.
Affect vs. effect – Very simply, if you can put the word the before your use of this word, you want to choose the one with the e. "The effect of misusing words affects both you and your readers." Effect is a noun, while affect is a verb. Look it up! See more at Copyblogger (along with additional grammar tips and articles for writers).
And if those tips, tricks and sources aren't enough, keep searching and learning by visiting some of these resourceful sites: Let GrammarBytes tell you about lay vs. lie and other rules; correct common mistakes (like using an instead of a before certain words) at WebGrammar; see Dr. Grammar to distinguish between accept and except and to cure a whole host of other word ailments with tricks, tips and resources; or get daily lessons in language at Daily Grammar.
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