After repeating this game of hide-and-seek many times, the dog begins to “associate the ____(气味) with a reward,” says Berkowitz.
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That's because dogs have millions of ____(嗅觉的) receptors, or smell nerves, in their noses.
Like humans, explains Bailey, monkeys have thumbs ____(可相对的) that face the hand's other fingers so monkeys can pick up objects.
Monkeys are perfect helpmates for quadriplegics, people ____(使瘫痪) from the neck down who are unable to use their own hands (and legs).
Monkeys are perfect helpmates for____(四肢瘫痪者) , people paralyzed from the neck down who are unable to use their own hands (and legs).