The Comma
SAT Reading & Writing · Rachel · Class 06 · October 10

The Comma

1. Joining Two Sentences

  • C1Two complete sentences can be joined by a comma plus and, but, so, or, yet, for or nor. Each side has its own subject and verb and could stand alone. The comma goes before the joining word, not after it.
    • The first trial failed, but the second trial produced usable data.
    • The sample was small, so the team repeated the survey.
    • The sample was small so the team repeated the survey.
    • The sample was small, so, the team repeated the survey.
  • C2A comma alone cannot join two complete sentences. Use a period or a semicolon, or add a joining word. Watch for words that look like an add-on to the first sentence but begin the second.
    • The first trial failed, the second trial produced usable data.
    • The first trial failed. The second trial produced usable data.
    • The archive opened in 1902. A gift from a local printer, it now holds 40,000 maps.
    • The archive opened in 1902, a gift from a local printer, it now holds 40,000 maps.
  • C3One subject with two verbs takes no comma before and. Check whether a new subject follows and.
    • The sensor records the temperature and transmits the data.
    • The sensor records the temperature, and transmits the data.
    • The sensor records the temperature, and it transmits the data.

SAT Questions

Question 1 · C1
After immigrating from Mexico and obtaining U.S. citizenship, Octaviano Ambrosio Larrazolo entered politics, earning a reputation for being a fervent defender of Hispanic civil rights. In 1919 Larrazolo was elected governor of ______ in 1928 he became the nation’s first Hispanic U.S. Senator.

Which choice completes the text so that it conforms to the conventions of Standard English?

  1. New Mexico and
  2. New Mexico,
  3. New Mexico, and
  4. New Mexico
Worked Answer

C. New Mexico, and

  1. Left of the blank: “In 1919 Larrazolo was elected governor of New Mexico” — a complete sentence.
  2. Right of the blank: “in 1928 he became the nation’s first Hispanic U.S. Senator” — a new subject (“he”) with its own verb (“became”): a second complete sentence.
  3. Two complete sentences joined by “and” need a comma before it → C.
Question 2 · C2
In modern plays, actors typically won’t acknowledge the ______ do so breaks the fourth wall, a metaphorical barrier between actors and audiences that allows viewers to suspend the knowledge that they’re watching a staged performance.

Which choice completes the text so that it conforms to the conventions of Standard English?

  1. audience. As to
  2. audience to
  3. audience. To
  4. audience, to
Worked Answer

C. audience. To

  1. Left of the blank: “actors typically won’t acknowledge the audience” — a complete sentence.
  2. Right of the blank: “To do so breaks the fourth wall …”. “To do so” is the subject and “breaks” is its verb: a second complete sentence.
  3. A comma alone cannot join two complete sentences; the period can → C.
Question 3 · C3
Conducted in 1946 by the U.S. Army Signal Corps, Project Diana’s successful radar contact with the Moon demonstrated the possibility of interplanetary communication and the precision of high-frequency radar ______ and inspired subsequent advances in radio astronomy.

Which choice completes the text so that it conforms to the conventions of Standard English?

  1. technology,
  2. technology
  3. technology;
  4. technology:
Worked Answer

B. technology

  1. Subject: “Project Diana’s successful radar contact with the Moon”. First verb: “demonstrated” (the possibility of … and the precision of …).
  2. After the blank comes “and inspired” — a second verb with the same subject, not a new sentence.
  3. One subject with two verbs takes no comma before “and” → B.

2. Clauses That Cannot Stand Alone

  • C4A clause that begins with although, because, when, while, if or as cannot stand alone. When it comes first, a comma follows it. No but is added after an although clause.
    • Although the first result was promising, the researchers repeated the trial.
    • Although the first result was promising, but the researchers repeated the trial.
    • When the pressure rises, the alarm sounds.
  • C5When such a clause comes last and gives the time, the condition or the reason, no comma comes before it.
    • The alarm sounds when the pressure rises.
    • The trial failed because the sensor overheated.
    • The alarm sounds, when the pressure rises.
  • C6A closing clause that sets up a contrast (whereas, although, while meaning “but”) takes a comma before it.
    • The northern slope stays wet, whereas the southern slope dries out by June.
    • The result was accepted, although the sample was small.
    • The northern slope stays wet, whereas, the southern slope dries out by June.