Also in 2025 Practice Test B English, question 53.
Passage The End of an Era
The End of an Era
(1) In 2004, the National Aeronautics and Space Administration (NASA) landed a rover, or robotic vehicle, named Opportunity on the surface of Mars. (2) The rover’s mission was to search for evidence of water and life on the planet. (3) The rover was designed to gather data on Mars for about 90 days, but Opportunity’s assignment did not come to an end until nearly 15 years later in 2019.
(4) During the rover’s mission, a high-resolution camera on the rover’s robotic arm took magnified photographs of the surface of Mars. (5) The photographs revealed small round rocks scattered across the surface of the planet. (6) The scientists nicknamed these rocks “blueberries” based on the rocks’ resemblance to the fruit. (7) These rocks were important because their spherical shape suggested that liquid water may have flowed over them for a substantial amount of time.
(8) Opportunity continued to provide valuable data about craters and other surface features. (9) Throughout the mission, the rover traveled a total of 28.06 miles across Mars’ surface. (10) When Opportunity had traveled nearly the length of a marathon, scientists celebrated the accomplishment by naming the valley that the rover was in Marathon Valley. (11) However, in 2018, a dust storm spread all over the planet, putting the rover’s progress on hold.
(12) Prior to this planet-wide dust storm, minor dust storms had periodically deposited a layer of dust onto the solar panels of the rover. (13) These prevented it from charging its batteries. (14) Scientists then had to rely on the passing winds and dust devils to clean off the solar panels. (15) After the massive 2018 dust storm subsided, scientists expected to be able to reestablish communication with Opportunity. (16) They made repeated attempts but to no avail. (17) In 2019, NASA finally declared Opportunity’s mission complete.
(18) Opportunity was an important asset in scientists’ study of Mars; it returned valuable data about our neighbor planet and survived powerful dust storms. (19) NASA described the mission of Opportunity as “one of the most successful and enduring feats of interplanetary exploration.” (20) Even though this rover’s journey ended, other rovers still roam the surface of Mars.
Question
What is the best way to combine sentences 12 and 13?
- APreventing the rover from charging its batteries, minor dust storms had periodically deposited a layer of dust onto the solar panels of the rover prior to this planet-wide dust storm.
- BPeriodically depositing a layer of dust onto the solar panels of the rover prior to this planet-wide dust storm, minor dust storms had prevented it from charging its batteries.
- CMinor dust storms, prior to this planet-wide dust storm, prevented the rover from charging its batteries because they had periodically deposited a layer of dust onto the solar panels of the rover.
- DPrior to this planet-wide dust storm, minor dust storms had periodically deposited a layer of dust onto the solar panels of the rover, preventing it from charging its batteries.
Show the answer
Correct answer: D
The question asks for the best way to combine sentences 12 and 13.
A. Incorrect. The phrase “this planet-wide dust storm” in the original sentence 12 makes a direct reference to sentence 11 and therefore acts as a transition that should be kept at the beginning. In this sentence, the transition phrase is placed at the end of the sentence, making the phrase confusing. In addition, the sentence is unnecessarily repetitive and wordy.
B. Incorrect. This combination unnecessarily turns sentence 12 into an overly long participial phrase, making the connection between “it” and its antecedent, “the rover,” unclear and distracting from the subject of the sentence, “minor dust storms.”
C. Incorrect. Not only does this combination move the reference to “this planet-wide dust storm” farther from sentence 11, but it is also unnecessarily wordy, adding “because” and repeating “the rover.”
D. CORRECT. This sentence efficiently and accurately adds sentence 13 to sentence 12 as a participial phrase by changing “These prevented” to “preventing,” while also retaining the meanings of the original sentences 12 and 13.
Question analysis
This sentence-combining question asks for the best way to join two sentences from the rover passage: one saying minor dust storms had periodically coated the rover's solar panels, the other saying this kept it from charging its batteries. The four versions keep the same facts in different orders, so students must judge which is clearest and most concise in context.
- Grade level
- Grade 8 reading and task
- Compared with grade 7
- Above grade 7 Combining two sentences is grade 7 work, usually with one version clearly better. These four are long, keep the same facts and differ in order and wording, so students must weigh clarity and concision across nearly identical sentences, more than typical.
- Estimated difficulty
- Hard: combines ideas, needs a plan, and has more than one tempting wrong answer.
- Thinking it demands
- Depth of knowledge 2, skills and concepts · mainly evaluate
- What makes it hard
- How sentences fit together moderate
- Every choice must be checked moderate
- Complex sentences minor
- Evidence
- Answered from one sentence or line
- Reading level
- Passage: about grade 11, 337 words; question and choices: about grade 13, 129 words.
- Corrected from the DOE handbook
- Two grammar terms in the explanation were corrected.
- Students, last 30 days
- Not enough answers yet to show (it takes 10).
Why it is hard, traps and wrong answers (shows the answer)
Why it is hard
None of the versions is plainly ungrammatical, so the ear gives little help, and the version with “because” looks best to students who value a clearly stated cause. Its cost is wordiness and a weaker link: the result comes first and the reference back to sentence 11 is buried mid-sentence. The question rewards keeping the original order, cause then effect, and folding sentence 13 in as a short closing phrase.
How sentences fit together moderate Working it out
“Prior to this planet-wide dust storm” points back to sentence 11, so the best version keeps it first; three versions move it later, which loosens the link between the two sentences. (Halliday & Hasan, 1976)
Every choice must be checked moderate Choosing the answer
All four versions keep every fact of sentences 12 and 13 and run 29 to 32 words, so none can be ruled out by content; order, pronouns and repetition decide. (Embretson & Wetzel, 1987)
Complex sentences minor Understanding the question
Each version is one long sentence built around a participial phrase or a “because” clause, and at that length a stranded “it” or a doubled “the rover” is easy to miss. (Abedi & Lord, 2001; Freedle & Kostin, 1993; Messick, 1989)
Strategy: Read sentence 11 first, then compare the versions on how smoothly each connects to it, how many words it uses, and whether every pronoun has a clear antecedent.
Traps
- Wordy, vague or informal: A revision is grammatical but wordy, imprecise or too casual for the passage.
- Unclear pronoun: A pronoun whose reference is vague or ambiguous, or one in the wrong case.
The wrong answers, classified
A Wordy, vague or informal (Connors & Lunsford, 1988)
Opens with the effect as a participial phrase, which pushes “prior to this planet-wide dust storm,” the link to sentence 11, to the end and names “the rover” twice.
B Unclear pronoun (Connors & Lunsford, 1988)
Packs sentence 12 into a 19-word opening phrase, so “it” follows “this planet-wide dust storm” and no longer points clearly to the rover buried inside the phrase.
C Wordy, vague or informal (Connors & Lunsford, 1988)
Likes the clear cause word “because,” but the result now comes first, “the rover” appears twice, and “prior to this planet-wide dust storm” splits the subject from its verb.
What was corrected from the DOE handbook, and why
- Explanation: The DOE’s explanation of Option B says the combination turns sentence 12 into “an overly long dependent clause,” and its explanation of Option D says Option D adds sentence 13 to sentence 12 “as a dependent clause” by changing “These prevented” to “preventing.” Neither is a clause: “Periodically depositing a layer of dust onto the solar panels of the rover prior to this planet-wide dust storm” (Option B) and “preventing it from charging its batteries” (Option D) have no subject or finite verb of their own. Both are participial phrases, and the site now calls them that. The reasoning and the answer, Option D, are unchanged.
Working it out, step by step
Figure out what the question asks
This question asks for the best way to join sentences 12 and 13 into one sentence. The best version keeps the meaning, uses few words and is clear. It should also connect smoothly to sentence 11, the sentence before.
Read the sentences in order
Sentence 11 tells about the giant 2018 dust storm. Sentence 12 begins “Prior to this planet-wide dust storm.” Prior to means before. That phrase points back to sentence 11, so it works best at the start. Sentence 12 says small storms put dust on the solar panels. Sentence 13 gives the result: “These prevented it from charging its batteries.”
Learn the tool: a participial phrase
A participial phrase is a group of words built on a verb form, often an -ing word. It describes something, but it has no subject and can’t stand alone. Example: The dog ran to the door. It wagged its tail. becomes The dog ran to the door, wagging its tail. Choice D does this. It turns “These prevented” into “preventing.”
Check each choice
- A is wrong. It starts with the result. It moves “prior to this planet-wide dust storm” to the end, far from sentence 11. It also says “the rover” twice.
- B is wrong. Its long opening phrase hides the rover. Then “it” comes after “minor dust storms,” so it is hard to tell what “it” means.
- C is wrong. It adds “because,” puts the result first and says “the rover” twice. It is wordier than D.
- D is right. It keeps the link to sentence 11 first, gives the cause, then adds the result as a short participial phrase.
Watch out: C looks clear because “because” names the cause. But it is longer, and it puts an extra phrase between “Minor dust storms” and its verb.
Choose the answer
So the answer is D: “Prior to this planet-wide dust storm, minor dust storms had periodically deposited a layer of dust onto the solar panels of the rover, preventing it from charging its batteries.”
Why this answer and not the closest wrong one
C is the closest wrong answer, because “because” makes the cause very clear. But C puts the result first and repeats “the rover.” D keeps the original order, cause then result. It also keeps the link to sentence 11 up front, in fewer words.
More questions like this
The original DOE question
The passage “The End of an Era” as printed (page 60)
