21.填空题（25分）A rat or pigeon might not be the obvious choice to tend to someone who is sick, but these creatures have someunderline(输入答案) skills that could help the treatment of human diseases. Pigeons are often seen as dirty birds and an urbanunderline(输入答案), 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 underline(输入答案) of your index finger, pigeons have a very impressive underline(输入答案)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 underline(输入答案) with spreading disease rather thanunderline(输入答案) it, but this long-tailed animal is highlyunderline(输入答案). 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 detectunderline(输入答案) 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 underline(输入答案)a sample is infected. Traditionally, a hundred samples would take lab technicians more than two days to underline(输入答案), 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

21.填空题（25分） A rat or pigeon might not be the obvious choice to tend to someone who is sick, but these creatures have some $\underline{输入答案}$ skills that could help the treatment of human diseases. Pigeons are often seen as dirty birds and an urban $\underline{输入答案}$, 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 $\underline{输入答案}$ of your index finger, pigeons have a very impressive $\underline{输入答案}$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 $\underline{输入答案}$ with spreading disease rather than$\underline{输入答案}$ it, but this long-tailed animal is highly$\underline{输入答案}$. 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 $\underline{输入答案}$ 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 $\underline{输入答案}$a sample is infected. Traditionally, a hundred samples would take lab technicians more than two days to $\underline{输入答案}$, 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