2023年6月英语六级（第1套 · 含听力）选词填空

Scientists recently examined studies on dog intelligence and compared them with research into the minds of other intelligent animals. The researchers found that dogs are among the more intelligent carnivores (食肉动物), social hunters and domestic animals, but that their intelligence does not __26__ other intelligent animals in any of those categories. Though a significant body of research has examined dog cognition __27__, the authors of this new study found little to warrant the __28__ of work that has been devoted to the topic.
Stephen Lea, lead author of the new study, argues that many researchers seem to have designed their studies to __29__ how clever dogs are, rather than simply to study dogs' brains. Lea and a colleague examined more than 300 studies of dog cognition, comparing the studies' results with those from research into other animals. The researchers made specific comparisons between the different species in different categories of intelligence. These comparisons __30__ that dogs are intelligent, but their intelligence is not as __31__ as some researchers might have believed.
In many areas, though, comparisons were not possible. For example, the researchers noted that both dogs and cats are known to be able to recognize and __32__ human voices. But the investigators could not find any data to indicate which species can remember a greater number of __33__ human voices, so it was impossible to compare the two on that front. However, not all researchers agree __34__ with the findings of this study. Zachary Silver, an American researcher, believes the authors of the new study __35__ the idea that an excessive amount of research has been devoted to dogs, as the field of dog cognition is young, and there is much to be learned about how dogs think.