What causes the vibrant colors of the aurora borealis? When charged particles from the sun collide with gases in Earth's...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

What causes the vibrant colors of the aurora borealis?

• When charged particles from the sun
  • collide with gases in Earth's upper atmosphere,
• the interaction
  • produces light in various wavelengths;
• consequently,
  • the display
    • (?) visible as dancing curtains of green, red, and purple light.

Understanding the Meaning

The passage starts with a question:

• 'What causes the vibrant colors of the aurora borealis?'
  • Setting up the topic we're exploring.

Now the sentence explains the answer:

• 'When charged particles from the sun collide with gases in Earth's upper atmosphere,'
  • This describes the condition - when this collision happens.
• 'the interaction produces light in various wavelengths;'
  • The interaction (between those charged particles and atmospheric gases) creates light in different wavelengths.

The sentence continues with a semicolon and "consequently":

• This signals we're about to learn the result of what was just described.

Now here's where we need to fill in the blank:

• 'the display _____ visible as dancing curtains of green, red, and purple light.'

Let's look at our choices:

• A. is (singular)
• B. are being (plural)
• C. have been (plural)
• D. are (plural)

What do we notice about the subject here?

• The subject of this verb is 'the display'
  • This is a singular noun - one display
  • It refers to the aurora borealis display that results from the interaction
• We need a verb that matches this singular subject
  • 'Is' matches 'the display' (singular)
  • We also need simple present tense because we're describing what generally happens when this phenomenon occurs

So we need A. is - it agrees with the singular subject 'the display' and uses the appropriate tense for describing a general phenomenon.

GRAMMAR CONCEPT APPLIED

Matching Verbs to Their Subjects in Number

When you need to choose the correct verb form, you must identify the subject of that verb and determine whether it's singular or plural. The verb must match the subject in number (called subject-verb agreement in grammar terms):

Pattern:

• Singular subject → Singular verb
  • The display is visible
  • The interaction produces light
• Plural subject → Plural verb
  • The colors are vibrant
  • The particles collide with gases

Common trap to avoid:

• Don't be distracted by other nouns near the verb
• In this question: "the interaction produces light in various wavelengths; consequently, the display _____ visible"
• Students might see "wavelengths" (plural) right before the blank
• But the subject is "the display" (singular), not "wavelengths"
• Always trace back to find the true subject

Application to this question:

• Subject: "the display" (singular)
• Verb needed: singular form
• Correct choice: "is" (singular present tense)