Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.
Example: Sentence: The Obama administration is developing additional screening protocols for airline passengers both overseas and in the United States to control infectious diseases such as Ebola, President Barack Obama said Monday .<sep>Span: Obama administration
Example solution: What was the duration of the Obama administration?
Example explanation: It is an inquisitive question based on the specific span of the sentence.

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?