"Grammar is a piano I play by ear," Joan Didion once observed. "All I know about grammar is its power." And what an awesome power it is.

However firm or tenuous your understanding of its myriad rules and conventions, grammar empowers you. It allows you to capture, shape and convey your thoughts to the world through 26 characters and a few simple punctuation marks. It's really quite an amazing symbolic system when you think about it.

But it is complex. You could devote your entire life to learning its rules and conventions, and still make occasional errors. For the everyday writer, many errors result from failing to connect one thought with another.

Take subject-verb agreement. It's a simple rule. Singular subjects take singular verbs. Plural subjects take plural verbs. It should be "This elm tree is gorgeous," not "This elm tree are gorgeous." Likewise, it should be "This row of elm trees is gorgeous," not "This row of elm trees are gorgeous," because the singular word row is the subject. The prepositional phrase with its plural object, of elm trees, doesn't alter the singular-singular connection.

Much of grammar is a matter of making the right connections. In the sentence "This row of elm trees is gorgeous," the subject is row, not trees, so the verb should be is, not are. The verb connects with the subject, not necessarily with the word that immediately precedes it.

Of course, there are (not there is) many exceptions. Some words appear to be singular but function either as singular or plural. In this sentence, "There is a lot of thought behind this decision," a lot has a singular sense and so takes a singular verb, but in this sentence, "There are a lot of reasons to make this decision," a lot has a plural sense and so takes a plural verb.

Likewise, compare "A number of you are thoughtful people" and "The number of thoughtful people seems to be declining." A number of takes the plural; the number of takes the singular.

Failure to think ahead and make connections accounts for another common writing error: misplaced and dangling modifiers. Again, the rule is simple. When a sentence begins with a modifying phrase or clause, the first words after the comma must be the thing modified, as in "When loaded, your program is ready to launch," not "When loaded, you are ready to launch your program." Failure to connect the modifying phrase when loaded with the thing modified, program, results in an unintended meaning — and probably an unfortunate outcome.

Do you see where the connection fails in this sentence: "As a health professional, I know you understand the importance of vaccinations"? Health professional refers to you, not I. "I know as a health professional you understand the importance of vaccinations" is still ambiguous. The intended connection is made when the words are arranged in this order (with or without the commas): "I know you, as a health professional, understand the importance of vaccinations."

To avoid many common grammatical errors, connect your thoughts.

Stephen Wilbers offers training seminars in effective business writing. E-mail him at wilbe004@umn.edu. His website is www.wilbers.com.