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来源：雅诚德英语网
Next the researcher introduced a third option, a third paddle that would initiate a new trial, giving the dolphin the choice of passing on difficult trials.
接下来，研究人员引入了第三种选择，用第三只桨启动一个新的试验，让海豚选择跳过困难的试验。
Next the researcher introduced a third option, a third paddle that would initiate a new trial, giving the dolphin the choice of passing on difficult trials.
接下来，研究人员引入了第三种选择，用第三只桨启动一个新的试验，让海豚选择跳过困难的试验。