PrepTest 109, Section 1, Question 23
An air traveler in Beijing cannot fly to(35 more words not shown)
The pattern of reasoning exhibited(16 more words not shown)
- AA doctor cannot(43 more words not shown)
- BAn ice-sculpture artist(45 more words not shown)
- COne cannot properly(34 more words not shown)
- DIt is impossible(60 more words not shown)
- EIn the City(49 more words not shown)
Reading the argument
That's a lot of connections, but the conclusion makes sense. To fly from Beijing to Lhasa, you must first reach Chengdu. To reach Chengdu from Beijing, you must first go to Xian. So a trip to Lhasa can't skip Xian.
Think of the required sequence: Beijing, then Xian, then Chengdu, then Lhasa. Each required connection carries the earlier requirement along with it. We aren't told that going to Xian guarantees you'll finish the trip. We're told that you cannot finish the trip without going there.
What we’re looking for
For the parallel question, look for two requirements that link together. Reaching the final stage requires an intermediate stage, and reaching that intermediate stage requires an earlier one. Therefore, reaching the final stage requires the earlier one too. Beijing supplies the starting context here; we don't need every answer to name four places or four stages to repeat that reasoning.
Working the answers
- A
The first requirement is promising: prescribing porozine requires first prescribing anthroxine. But then the answer switches to anthroxine's possible side effects. Most patients feel drowsy or nervous, and the conclusion singles out nervousness as likely.
We need a second required step linked to the first, not alternative effects that occur in most patients. A doesn't establish that taking the first medicine requires having felt nervous in the way reaching Lhasa requires passing through Xian.
- BCorrect
Yellow requires green, just as reaching Lhasa requires reaching Chengdu. Green requires white, just as reaching Chengdu requires going through Xian. So yellow requires white: the final achievement carries the earlier requirement with it.
The colors replace the three destinations in the chain. Beijing doesn't need its own color counterpart because it simply fixes where the travelers start. B fully preserves the two linked requirements and the conclusion they support.
- C
A microscope can be used. Must it be used? That is the missing step.
Identifying the mushroom requires examining its spores, but the answer merely offers one way to examine them. Perhaps another method would work. C then treats this available method as a requirement. The original never makes that move: flying to Xian is explicitly required, not just one possible route to Chengdu.
- D
This branches into two ways to learn grammar: difficult study or growing up around the language. Our argument links required stops in a single chain; it doesn't offer two alternative routes.
D also moves from ways of meeting a requirement for fluency to ways of achieving fluency. Knowing the grammatical rules is necessary, but we haven't been told that it is all someone needs. Neither the branching structure nor that final move matches the flight argument.
- E
Every Giselle dancer also danced in Sleeping Beauty, but only some Sleeping Beauty dancers also danced in Swan Lake. Those Swan Lake dancers might be entirely different people from the Giselle dancers. We can't carry the first group through the second relationship.
To match the required connections, we'd need every relevant Sleeping Beauty dancer to have danced in Swan Lake. “Some” leaves the overlap in the conclusion unestablished.
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