Tip #16 Conventions of Standard English: Principle 3: Know when conjunctions require commas and when they don't

.

Principle 4: Conjunctions & Commas
Core Rules:

1. No Comma Needed:
   • Joined subjects with one verb (The cat and the dog play).
   • Joined verbs with one subject (She runs and swims).
   • Joined objects with one verb (He bought apples and oranges).
2. Comma Required:
   • Joining two independent clauses (IC, conjunction IC).

• I study daily, but I struggle with math.

Conjunctions to Memorize (FANBOYS):

• For, And, Nor, But, Or, Yet, So.

Practice

1. No Comma: Joined Subjects
Passage (55 words):
The rapid melting of Arctic ice _______ the increasing frequency of extreme weather events are both consequences of climate change. Scientists warn that these interconnected phenomena could accelerate global sea-level rise by 2050.
A. and
B. , and
C. but
D. , but
Answer: A ("melting" and "events" are joined subjects sharing the verb "are." No comma needed.)
Strategy:

• Identify the structure: Subject 1 + Subject 2 + Verb.
• Eliminate commas if the conjunction joins subjects/verbs/objects only.

2. Comma Required: Independent Clauses
Passage (60 words):
The novelist spent years researching the historical period _______ she wanted to ensure the setting felt authentic to readers. Her dedication paid off when critics praised the book’s vivid detail.
A. , and
B. and
C. , so
D. so
Answer: A (Two ICs: "The novelist spent years..." and "she wanted to ensure...")
Strategy:

• Check if both clauses before/after the blank can stand alone.
• If yes, use a comma + FANBOYS.

3. No Comma: Joined Verbs
Passage (58 words):
The software update fixed critical security flaws _______ improved the user interface significantly. Developers credited the improvements to feedback from beta testers.
A. , and
B. and
C. , but
D. but
Answer: B ("fixed" and "improved" are joined verbs sharing the subject "update.")
Strategy:

• Joined verbs with one subject → no comma.

4. Comma Required: Contrast
Passage (65 words):
The artist’s early work was dismissed as derivative _______ her later pieces revolutionized the genre. Critics now regard her as a pioneer whose influence spans generations.
A. , but
B. but
C. , and
D. and
Answer: A (Contrasting ICs require a comma + "but.")
Strategy:

• Look for contrast keywords (but, yet).
• If contrasting ICs, comma is mandatory.

5. No Comma: Joined Objects
Passage (52 words):
The treaty aimed to reduce carbon emissions _______ promote renewable energy investments. Analysts argue its success hinges on enforcement mechanisms.
A. , and
B. and
C. , or
D. or
Answer: B ("reduce" and "promote" share the verb "aimed." No comma for joined objects.)
Strategy:

• Joined objects/verbs → no comma.

Practice
Passage (70 words):
The documentary examines the rise of renewable energy in developing nations _______ it highlights the challenges of transitioning from fossil fuels. Interviews with engineers and policymakers reveal both optimism and skepticism about the timeline for net-zero emissions.
A. , and
B. and
C. , yet
D. yet
Answer: A (Two ICs with additive relationship.)
Strategy:

• Both clauses are independent.
• No contrast → "and" is better than "yet."