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 (嗅觉感受器), 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 to 10 , but for a rat it takes less than 20 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)associated (B)examine (C)indicate (D)nuisance (E)peak (F)preventing (G)prohibiting (H)sensitive (I)slight (J)specify (K)superior (L)suspicious (M)tip (N)treated (O)visual