Understanding the Passage: Breathalyzer Test Steps

The passage describes the process of a roadside breathalyzer test used to detect alcohol in a driver's breath. We are given the first sentence (S1) and the last sentence (S6), and we need to arrange the four jumbled sentences (P, Q, R, S) in the correct order to form a coherent paragraph that logically flows from S1 to S6.

Analysing the Sentences (S1 to S6)

• S1: At the roadside, the driver will be asked to blow through a small glass tube into a plastic bag. (This sentence introduces the initial action of the breathalyzer test).
• S6: The driver will be asked to go to the police station. (This sentence states a potential consequence that follows the test result).
• P: And if the colour change does not reach the line the driver cannot be punished under the new law. (This sentence describes an outcome based on the colour change being below a certain threshold).
• Q: Inside the tube are chemically treated crystals which change colour if the driver has alcohol on his breath. (This sentence explains the mechanism that causes the colour change mentioned in S1).
• R: But if the colour change does reach the line then the test has proved positive. (This sentence describes an outcome based on the colour change reaching a specific threshold, and the phrase "But if" suggests it contrasts with a previous condition).
• S: If the colour change goes beyond a certain line marked on the tube this indicates that the driver is probably over the specified limit. (This sentence describes an outcome based on the colour change exceeding a higher threshold).

Finding the Logical Sentence Sequence

The passage starts with S1, describing the action of blowing into the tube. The next logical step in describing the breathalyzer test is to explain how the tube works or what happens inside it. Sentence Q explains that the tube contains crystals that change colour when alcohol is present. Therefore, Q should immediately follow S1.

After explaining the mechanism (Q), the passage needs to describe how the colour change is interpreted. Sentences S, P, and R discuss these interpretations based on different levels reached by the colour change relative to a line on the tube.

Let's look for connections between S, P, and R. Sentence P talks about the colour change "not reach[ing] the line," and sentence R talks about the colour change "does reach the line." Sentence R starts with "But if," which clearly contrasts with the condition in P ("if the colour change does not reach..."). This indicates that P should come immediately before R, forming the pair PR.

Now we have the sequence Q followed by the pair PR, with sentence S remaining. Let's consider the order QSPR, which is one of the options.

Evaluating the Q S P R Sequence

Let's see if the sequence QSPR forms a coherent paragraph when placed between S1 and S6:

• S1: At the roadside, the driver will be asked to blow through a small glass tube into a plastic bag. (Start)
• Q: Inside the tube are chemically treated crystals which change colour if the driver has alcohol on his breath. (Explains the mechanism, naturally follows S1).
• S: If the colour change goes beyond a certain line marked on the tube this indicates that the driver is probably over the specified limit. (Describes a specific positive outcome - exceeding a higher threshold).
• P: And if the colour change does not reach the line the driver cannot be punished under the new law. (Describes the negative outcome - below the threshold).
• R: But if the colour change does reach the line then the test has proved positive. (Describes the basic positive outcome - reaching the threshold, contrasts with P).
• S6: The driver will be asked to go to the police station. (Consequence, follows from a positive test result).

In this sequence, Q explains the mechanism. Then S describes the result if the colour change indicates being over the limit (a high reading). P describes the result if the colour change is insufficient (a negative reading). R then describes the basic positive result (reaching the line), contrasting with the negative case described in P ("But if... does reach..." vs. "if... does not reach..."). Finally, S6 follows the positive test result. While discussing the 'beyond' case (S) before the 'not reaching' (P) and 'reaching' (R) cases might seem counter-intuitive in terms of linear threshold progression, the strong P-R link and the need to place Q first make QSPR a valid and coherent order among the given options.

Step-by-Step Analysis and Conclusion

Following the analysis of connections and flow:

1. S1 introduces the action.
2. Q explains the scientific basis of the action, following S1.
3. S describes a specific level of positive outcome (exceeding a line).
4. P describes the negative outcome (not reaching the line).
5. R contrasts with P, describing the general positive outcome (reaching the line), solidifying the PR connection.
6. S6 describes the consequence following a positive result.

The sequence QSPR aligns with a logical progression from the test mechanism to interpreting different potential outcomes based on colour change thresholds, leading to the final consequence. Therefore, the proper order for the four sentences is QSPR.

Revision Table: Passage Structure

Additional Information: Solving Sentence Order Questions

Sentence rearrangement, or passage completion, questions require careful reading and understanding of context, grammar, and logical flow. When tackling these questions:

• Start by reading the fixed sentences (S1 and S6) to get the overall theme and boundaries.
• Read the jumbled sentences (P, Q, R, S) multiple times to understand the individual points they make.
• Look for explicit or implicit links between sentences, such as transition words ("But," "And," "Therefore"), pronoun references (he, she, it, they), or chronological order of events or steps in a process.
• Identify sentences that introduce a topic or concept (often good candidates for early positions) and sentences that conclude or summarise (often good candidates for later positions).
• Pay close attention to sentences that seem to form a pair or a short sequence due to contrasting ideas, cause-and-effect relationships, or sequential steps.
• Once you think you have found the correct order, read the complete paragraph from S1 to S6 with your proposed sequence inserted, checking if it reads smoothly and makes logical sense.