Several readers have sent in questions regarding comma use. I’ll take them in turn.
1. Does a comma always go before the word too?
Whether or not a writer places a comma before the word too depends upon the desired emphasis.
Too is an adverb meaning “in addition, furthermore, moreover, besides, also.”
The only reason to place a comma before the too is to slow the pace of the sentence or change the emphasis:
My dog can fetch the paper too.
My dog can fetch the paper, too.
The same option applies when the too comes within the sentence:
I too can recite the Gettysburg Address.
I, too, can recite the Gettysburg Address.
A note in the CMOS (Chicago Manual of Style) recommends that we use commas with too only when we want to emphasize an abrupt change of thought. The editor gives this memorable example:
He didn’t know at first what hit him, but then, too, he hadn’t ever walked in a field strewn with garden rakes.
In most cases, commas with too are unnecessary.
2. Is it correct to place a semicolon before however and a comma after it?
The building was completely remodeled on the inside; however, the 18th century façade was left unaltered.
3. Is it necessary to place a comma before “as well as”?
You don’t need a comma before “as well as” when it introduces words that are essential to the meaning of the entire sentence:
I like mysteries as well as historical novels.
The no-smoking policy applies to teachers as well as to students.
The “as well as” phrase is enclosed with commas if–like a non-restrictive clause–it can be left out without affecting the meaning of the main clause:
Mysteries, as well as historical novels, rank high on my list of favorites.
The teachers, as well as the students, must respect the no-smoking policy.
4. Can you replace a semicolon with a comma?
No, with certain exceptions.
The semicolon is stronger than a comma, but not as strong a stop as a period. Its usual job is to separate independent clauses that are closely related in thought.
Grandpa patiently fed the kitten with an eye-dropper; he’d always had a soft spot for baby animals.
Sometimes, if the clauses are very short, commas can replace semicolons or coordinating conjunctions to achieve literary effect, as in the usual translation of Julius Caesar’s famous “Veni, vidi, vici”: “I came, I saw, I conquered.”