Engineers often describe an enclosure made from a magnetically responsive alloy as redirecting an external magnetic field around whatever the enclosure contains. The resulting protection is rarely ______ gaps where panels meet can guide some of the field inward, and an intense field can overwhelm the alloy's shielding capacity.
Which choice completes the text so that it conforms to the conventions of Standard English?
For boundary questions involving "however," first determine which clause the word belongs to and whether it is an interrupting adverb. Then evaluate the surrounding clauses: if both are independent, they need a semicolon or another valid sentence boundary, while the interrupting adverb must also be set off with the appropriate comma.
Hints
Find complete thoughts
Determine whether the text before the blank and the text beginning with "gaps" each contain a subject, a verb, and a complete thought.
Examine "however"
Consider whether "however" is essential to the grammatical structure of the first clause or functions as an interrupting adverb.
Check both boundaries
The correct choice must punctuate both the interruption created by "however" and the boundary between the two complete clauses.
Step-by-step Explanation
Identify the clauses
"The resulting protection is rarely complete in practice" is an independent clause. The text beginning with "gaps where panels meet can guide" also forms an independent clause.
Punctuate the interruption
At the end of the first clause, "however" contrasts that clause with the preceding description of how shielding works. Because "however" is a nonessential interruption, a comma must separate it from the rest of the clause.
Join the independent clauses
The two independent clauses are not connected by a coordinating conjunction. A semicolon should therefore follow "however," producing "complete in practice, however; gaps where panels meet can guide some of the field inward."