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).
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Most trainers condition animals by using positive ____(强化), rewarding an animal for doing something correctly, says animal behaviorist Bailey.
“Dogs love to ____(取回) objects so the towel becomes a reward,” says Morris Berkowitz, who heads up a canine drug-sniffing program in New York.
Today, dogs may be employed to sniff out illegal substances in school lockers or earthquake victims buried beneath the ____(碎石) of a collapsed building or highway.
Primates may not be good____(嗅探者) , but they can certainly lend a helping hand or two.