In September, more than a dozen whales beached themselves in the Canary Islands. Rescuers tried to water down the whales and keep them cool. But all of them【C1】______died. Nearby, NATO naval forces were【C2】______echo sounding devices meant to【C3】______an enemy"s submarines, and public【C4】______of the deaths ultimately came to【C5】______suspicions of a link between whale distress and loud ocean noises. The theory is that the mammals seek to【C6】______the roar of the deep, rush toward the surface and in some cases end up going【C7】______. For decades, environmentalists have worked to reduce the undersea noise—usually with【C8】______success, given the growing industrialization and militarization of the oceans. They have【C9】______ suits and waged letter-writing campaigns, 【C10】______a recent petition that asks the United States Navy to【C11】______its testing of underwater sound equipment. The discovery by biologists in Hawaii that whales can【C12】______the sensitivity of their hearing to protect their ears from loud noise adds another dimension to the【C13】______. Michael Jasny, a senior policy analyst, called the research fascinating and said he hoped it would prove【C14】______ in protecting whale hearing from these threats. But he【C15】______the finding as a work in【C16】______that posed many unanswered questions. "A lot more work needs【C17】______," he said. "Could it be replicated in the wild? It"s a huge question." 【C18】______whales could learn to decrease the sensitivity of their hearing, Mr. Jasny said, that would【C19】______only a relatively small part of the oceanic noise problem. "It"s important to understand that it"s【C20】______," he said of the proposed method. "It won"t be a silver bullet."