Assertion: porpoise | /r/HasProperty | 9–28 kilometres per hour
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Source sentences:
text: Porpoises are fast swimmers in comparison to seals, which typically cruise at 5–15 kn, or 9–28 kilometres per hour (5.6–17.4 mph); Dall's porpoise, in comparison, can travel at speeds up to 74 kilometres per hour (46 mph).