Detailed Instructions: Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.
Problem:Sentence: Investigators have used ground - penetrating radar and specialized GPS devices to peek below the landscape , but no one is entirely certain why the holes form along the surface of this landmark , which attracts thousands of visitors each year .<sep>Span: GPS devices
Solution:
Is this different from the GPS devices we use on a daily basis?