Question 98·Medium·Transitions
Researchers have long sought to harness tidal power for electricity. Early prototypes were unreliable and costly; ______ new composite materials and digital monitoring systems have made tidal turbines more efficient and durable.
Which choice completes the text with the most logical transition?
For transition questions, first cover the choices and read the sentence without the transition; decide the logical relationship between the ideas (addition, example, contrast, cause/effect, summary). Then classify each answer choice by what kind of relationship it usually signals, and pick the one that matches the logic you already identified—not what “sounds good.” If more than one seems okay, reread the sentence carefully and eliminate any choice that slightly changes the meaning or suggests the wrong relationship (like similarity instead of contrast).
Hints
Read the sentence without the blank
Ignore the blank and read the two parts of the sentence together. Decide what the first part is saying and what changes in the second part.
Decide the relationship between the ideas
Ask yourself: Is the second part giving an example of the first, adding a similar idea, explaining a reason, or showing a contrast (a change or opposite situation)?
Check each option’s typical use
Think about when you normally use phrases like "for example," "similarly," and "after all" in writing. Which one does not fit a shift from a problem in the past to an improvement now?
Test choices in the sentence
Substitute each transition into the sentence and see which makes the logical connection between "unreliable and costly" and "more efficient and durable" clearest.
Step-by-step Explanation
Understand what each part of the sentence is saying
Read the sentence without any transition:
"Researchers have long sought to harness tidal power for electricity. Early prototypes were unreliable and costly; ___ new composite materials and digital monitoring systems have made tidal turbines more efficient and durable."
The first part says early prototypes were unreliable and costly (a problem). The second part says new materials and systems have made turbines more efficient and durable (an improvement).
Identify the relationship between the two parts
Ask: How does the second part relate to the first?
- The first part: difficulty and failure (unreliable, costly).
- The second part: progress and success (more efficient, durable).
This shows a shift from negative to positive, so the relationship is a contrast between older problems and newer improvements, not an example, similarity, or explanation.
Match the relationship to the correct type of transition
Now match this contrast relationship to the answer choices:
- One choice should signal a contrast between what came before (problems) and what comes after (improvements).
- The other choices signal things like giving an example, adding a similar point, or explaining a reason, which do not fit the negative-to-positive shift here.
The only option that correctly signals this contrast and makes the sentence logically coherent is "however," so the answer is D) however,.