English: Punctuation That Does a Job

This is Unit Two of ACT Preparation: punctuation that does a job. Unit one ended by asking where each independent clause begins and ends; this unit answers that question one mark at a time. Carry one rule. Every mark has a job, and every error is a mark doing the wrong job or none at all. A comma that cannot name its job is the comma to delete. By the end of this part you will be able to place a comma before a joining conjunction and after an introductory element. To decide whether information is essential, and punctuate it to match. To use the serial comma and remove commas that do no job. And to use apostrophes for possession and contraction while keeping them off plurals and possessive pronouns.

Two entries on commas that join clauses and close an introduction.

The comma that joins two clauses.

ACT 0101 Comma Before a Joining Conjunction

When a coordinating conjunction joins two independent clauses, a comma goes before the conjunction, the same join that repairs a comma splice. In "the rain stopped, and the game resumed," a full sentence stands on each side of and. When and links two words or phrases instead, no comma comes before it.

The comma that closes an opening.

ACT 0102 Comma After an Introductory Element

A comma follows an introductory element at the start of a sentence: a subordinate clause, a phrase, or a transitional word such as however. "After the storm passed, crews cleared the roads." The comma marks where the main clause begins, so it follows the whole introduction, never part of it.

Seven entries on the unit's center: whether information is essential, and what that decides about commas.

Detail the sentence can do without.

ACT 0103 Nonessential Information

Nonessential information adds detail but is not needed for the sentence's basic meaning, so commas set it off: a pair in mid-sentence, or one comma at the end. In "my mother, who lives in Denver, visits every June," the same person visits with or without the clause. Dropping the closing comma breaks the pair.

Information the sentence needs.

ACT 0104 Essential Information

Essential information tells the reader which one is meant. Without it, the sentence turns too general or changes meaning, so it takes no commas. "Students who finish early may leave" means only those students; set off with commas, the clause would let every student leave.

A test that tells the two apart.

ACT 0105 The Removal Test

To test information, remove it and reread. If the meaning is unchanged, it was nonessential and takes commas; if the meaning blurs or changes, it was essential and takes none. Removing "which opened in May" leaves the same bridge. Test the meaning, not the length: a one-word name can be essential.

The two words that open these clauses.

ACT 0106 Which and That

That introduces essential information and takes no commas; which most often introduces nonessential information, set off by commas. "The bike that won the race is for sale" picks out one bike, while "our bike, which won the race, is for sale" adds a detail. A that-clause between commas is an error.

Names that identify.

ACT 0107 Essential Names

A name that tells which person is meant is essential and takes no commas: "the drummer Lena Ortiz played first." A name that renames someone already identified takes commas: "her only brother, Sam, drove." Ask whether, without the name, the sentence could mean someone else.

Punctuating a clause, step by step.

ACT 0108 Essential or Not: Commas Around a Clause

To punctuate a clause or name, mark where the information begins and ends, remove it and reread, then punctuate to match: commas for nonessential, none for essential, with that opening an essential clause. "The trail that starts behind the school is closed" needs its clause to say which trail, but in "Hawk Ridge Trail, which starts behind the school, is closed," the name already identifies it. The same clause can be essential in one sentence and nonessential in another.

An opening and an interruption together.

ACT 0109 An Introduction and an Interruption

A sentence can open with an introduction and also carry an interruption, and each needs its own commas. Find the independent clause, put a comma after everything before the subject, then set off any nonessential element with a comma on each side. "When the lights came up, Maria Santos, who had led the orchestra for thirty years, bowed." If the interruption has a comma on one side only, one of the pair has been lost.

Five entries on the serial comma and on the four places a comma never goes.

Commas in a list.

ACT 0110 Serial Comma

In a series of three or more items, a comma separates each item, including the one before the final and or or, the serial comma: "we packed water, maps, and a first-aid kit." Some style guides, such as AP, drop the final comma, and that is a style choice, not a grammar error.

The first place a comma never goes.

ACT 0111 No Comma Between Subject and Verb

A comma never separates a subject from its verb, or a verb from its object, however long the subject. "Everyone who stayed after the concert, helped stack chairs" wrongly cuts the subject off from helped. A long subject tempts a spoken pause, but only the closing comma of a pair may stand there.

The second place.

ACT 0112 No Comma Inside a Compound

When and joins two parts of a compound subject, verb or object, no comma goes before it, because that comma is for clause joins. "The crew repaired the roof, and painted the porch" has one subject, so the comma goes. No new subject means no new clause, and no comma.

The last two places.

ACT 0113 No Comma After a Series or Before That

No comma follows the last item in a series, and none comes before a that-clause reporting speech or thought. "Oak, maple, and birch, line the street" splits the subject, and "the coach said, that practice was canceled" splits said from its report. Each comma needs a job.

Finding the comma that does nothing.

ACT 0114 Finding the Comma With No Job

When a sentence carries too many commas, check each one against the jobs a comma can do and the four places it never goes. In "after the meeting, the new manager, explained, that the schedule, and the budget would change," the first comma ends the introduction and stays; the second cuts subject from verb, the third precedes a that-clause, and the fourth splits a two-part subject, so all three go. Check every comma, not only the one that looks odd.

Four entries on apostrophes: possession, contraction, and where an apostrophe never goes.

Showing who owns what.

ACT 0115 Apostrophe for Possession

For possession, a singular noun takes apostrophe s, a plural ending in s takes an apostrophe after the s, and a plural not ending in s takes apostrophe s: the dog's bowl, the dogs' bowls, the children's coats. Find the owner first, then the form.

The apostrophe's other job.

ACT 0116 Contractions, and Where Apostrophes Never Go

An apostrophe also marks a contraction, standing for missing letters, as in don't for do not. Apostrophes never form plurals, never go on verbs, and never go on possessive pronouns such as yours, its or whose. Plural and possessive sound alike, so ask whether anything is owned.

Two pronoun pairs.

ACT 0117 Its and It's, Whose and Who's

Its and whose are possessive pronouns with no apostrophe; it's means it is or it has, and who's means who is or who has. "It's raining, and the dog left its bowl outside." Expand the word: if it is or who is fits, keep the apostrophe; if not, drop it.

Apostrophe decisions, step by step.

ACT 0118 Possessive or Plural

An apostrophe question is answered by deciding whether the word shows ownership, stands for missing letters, or is a plain plural; then, for ownership, whether there is one owner or several; then applying the form, with no apostrophe ever on its or whose. In "the team's from three schools shared a field, and each schools' coach praised it's surface," teams is a plain plural, each school is one owner, and it's should be its. Possessive pronouns never take an apostrophe.

Look at what you can now do. You can place a comma before a conjunction that joins two clauses, and after the whole of an introductory element. You can decide whether information is essential by removing it, and punctuate to match: commas for nonessential, none for essential, that for an essential clause. You can use the serial comma and delete any comma that cuts a subject from its verb, splits a compound, follows a series, or stands before a reported that-clause. And you can use apostrophes for possession and contraction, never on plurals and never on its or whose. Part two turns to semicolons, colons, dashes and the end of the sentence.