Question 183·Hard·Boundaries
During the final descent, the spacecraft lost contact with _____ engineers were still able to confirm a successful landing via onboard telemetry.
Which choice completes the text so that it conforms to the conventions of Standard English?
For sentence-boundary questions, first test whether the text before and after the blank are each complete sentences (they have a subject and a verb and express a complete thought). If both are independent clauses, you generally need either a period, a semicolon, or a comma plus a coordinating conjunction (for, and, nor, but, or, yet, so). Eliminate options that create run-ons, comma splices, or misuse colons/semicolons, and choose the one that matches the standard patterns.
Hints
Check if both sides are complete sentences
Cover the blank and ask: Can the words before the blank stand alone as a complete sentence? Can the words after the blank also stand alone?
Think about how to connect two full sentences
If you do have two complete sentences, what are the correct punctuation options in Standard English to join them in one sentence?
Focus on the role of "but"
The word "but" is a coordinating conjunction showing contrast. When it connects two full sentences in the middle of a sentence, what usually appears right before it?
Step-by-step Explanation
Identify the clauses on each side of the blank
Read the part before the blank: "During the final descent, the spacecraft lost contact with" — this leads into the noun phrase that will be completed at the blank.
Read the part after the blank: "engineers were still able to confirm a successful landing via onboard telemetry" — this is a complete thought and can stand alone as a sentence.
Completing the noun phrase at the blank with "mission control" gives the first independent clause: "During the final descent, the spacecraft lost contact with mission control." The second is "engineers were still able to confirm a successful landing via onboard telemetry." So we have two independent clauses that need to be joined correctly.
Recall how to join two independent clauses
Two independent clauses can be joined in a few standard ways:
- With a comma + coordinating conjunction (for, and, nor, but, or, yet, so): e.g., ", but"
- With a semicolon by itself: e.g., ";"
- With a period, making two separate sentences.
When a coordinating conjunction like "but" is used to join two full clauses in one sentence, a comma normally appears right before it.
Check each punctuation choice against the rule
Test each option at the blank after "with":
- "mission control but" has no comma before the coordinating conjunction joining two independent clauses, creating a run-on.
- "mission control; but" is not standard because a semicolon already separates two independent clauses; adding "but" after it is redundant and nonstandard on the SAT.
- "mission control: but" misuses the colon; a colon introduces an explanation, list, or restatement of the preceding complete clause and would not be followed by "but."
Select the answer that correctly joins the clauses
We need a comma before the coordinating conjunction "but" to properly join the clauses: "During the final descent, the spacecraft lost contact with mission control, but engineers were still able to confirm a successful landing via onboard telemetry."
So the correct answer is "mission control, but."