Question 250·Easy·Boundaries
Astronomers initially classified Pluto as the ninth planet in the solar _____ subsequent discoveries of similar-sized bodies in the Kuiper Belt have led scientists to reconsider its status.
Which choice completes the text so that it conforms to the conventions of Standard English?
For sentence-boundary questions involving words like "however," first test whether the parts before and after the blank are complete sentences. If both are independent clauses, you cannot join them with just a comma or nothing at all. Recognize that transitions such as "however," "therefore," and "consequently" are conjunctive adverbs: when they connect two complete sentences in one line, they typically need strong punctuation (semicolon or period) before them and a comma after them. Then scan the choices for the one that matches this pattern and avoids comma splices or run-ons.
Hints
Check each side of the blank
Cover the blank and see if the words before it form a complete sentence. Then do the same for the words after it. Are both sides able to stand alone?
Focus on the word "however"
Notice that every answer choice includes the word "however." Think about what job "however" is doing in this sentence and how such a word is usually punctuated when it connects two complete thoughts.
Think about sentence boundaries
Because you have two complete sentences, you need punctuation strong enough to separate them and also to correctly set off the transition word. Ask yourself which choices are too weak (creating a comma splice or run-on) or incomplete.
Step-by-step Explanation
Identify the clauses around the blank
Read the part before the blank: "Astronomers initially classified Pluto as the ninth planet in the solar" (the missing word will complete the noun phrase). This portion forms an independent clause once "system" is added.
Now read the part after the blank: "subsequent discoveries of similar-sized bodies in the Kuiper Belt have led scientists to reconsider its status." This has a subject ("subsequent discoveries") and a verb ("have led") and is a complete thought. So the sentence has two independent clauses.
Understand the function of "however"
The word "however" shows contrast between the two ideas:
- First idea: Pluto was classified as a planet.
- Second idea: New discoveries have led scientists to reconsider that status.
Here, "however" is a transition word (a conjunctive adverb) connecting two complete sentences and signaling contrast.
Recall punctuation rules for transitions between sentences
When a transition word like "however" connects two independent clauses in the same sentence, you need:
- Strong punctuation before the transition (a period or semicolon) to end the first sentence, and
- A comma after the transition word when it introduces the second clause.
Using only a comma, or no punctuation at all, between two independent clauses creates errors like comma splices or run-on sentences.
Match the rule to the answer choice
You need an option that (1) correctly separates two independent clauses and (2) correctly punctuates the transition word "however" with a comma after it. Choice A "system; however," provides a semicolon before "however" (separating the two sentences) and a comma after "however" (punctuating the transition), so the correct answer is system; however,.