OG7 阅读 Q26

At the end of the third paragraph the author notes that the GPS tracking devices attached to the birds "determined each bird's flight position to within 30 cm." This detail, along with the author's mention in the same sentence of another device that measured the timing of the wing flaps, provides evidence for the inference that the author likely specified 30 cm to underscore Usherwood's use of precise data-collection methods.
Choice B is incorrect because the passage does not state that the distance an ibis flies between wing flaps was something that could be ascertained by Usherwood's study. Choice C is incorrect because the passage does not discuss the wingspan length of juvenile ibises or suggest that this length could be determined from Usherwood's tracking data. Choice D is incorrect because the passage does not discuss the distance maintained between the plane and the ibises in flight.