A rat or pigeon might not be the obvious choice to tend to someone who is sick, but these creatures have some 1 skills that could help the treatment of human diseases.Pigeons are often seen as dirty birds and an urban 2 , but they are just the latest in a long line of animals that have been found to have abilities to help humans. Despite having a brain no bigger than the 3 of your index finger, pigeons have a very impressive 4 memory. Recently it was shown that they could be trained to be as accurate as humans at detecting breast cancer in images.Rats are often 5 with spreading disease rather than 6 it, but this long-tailed animal is highly 7 . Inside a rat’s nose are up to 1,000 different types of olfactory receptors （唤觉感受器），whereas humans only have 100 to 200 types. This gives rats the ability to detect 8 smells. As a result, some rats are being put to work to detect TB （肺结核）. When the rats detect the smell, they stop and rub their legs to 9 a sample is infected.Traditionally, a hundred samples would take lab technicians more than two days to10, but for a rat it takes less than20 minutes. This rat detection method doesn’t rely on specialist equipment. It is also more accurate — the rats are able to find more TB infections and, therefore, save more lives.A. associatedB. examineC. indicateD. nuisanceE. peakF. preventingG. prohibitingH. sensitiveI. slightJ. specifyK. superiorL. suspiciousM. tipN. treatedO. visual