Back to this graphic again: unpredictable food supply occurred on the left but doesn't occur on the right.
再回到这张图,对左边的人而言,食物供给难以预计,而右边却并非如此
And later on if you right before or right during you give the dog some food you--you ping a bell the bell will cause the saliva to come forth.
,在喂食前或者喂食过程中,你摇铃,铃声就会加速唾液的分泌。
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