阅读理解。 The Year of the Dog has gone and this year we have pigs. What words can we think of for pigs? Some bad words maybe, like silly, dirty, greedy (贪婪)…But, are these true? When we see pigs, they are usually in dirty water or behind dirty fences. But pigs also want to be clean if they can. Pigs have no sweat glands( 汗腺), so they have to get cool in water when they feel hot. If people are greedy, we say they 'pig out'. Yes, pigs love eating a lot. But they are useful to people. People not only eat their meat, but also use other parts of pigs. Pig skin is used for glue and shoes. The hair can be used to make brushes. Sometimes, pigs are even used to make medicine. 'He is as silly as a pig!' This expression is wrong. Pigs are very smart animals. Among all animals, they are the third cleverest-monkeys, dolphins and pigs. Scientists think the training of pigs is easier than the training of dogs and cats. Pigs have a very good sense of smell (嗅觉). They can find things nearby or faraway. They can also help the police to sniff-out drugs (毒品) at an airport or at a train station. 1. In this passage, the writer mainly wants to tell us that _____. A. pigs are always very silly, dirty and greedy B. pigs are as clever as monkeys and dolphins C. people's ideas about pigs are not always correct 2. Pigs usually like to stay in water in hot weather because they can _____ there. A. clean themselves B. drink water C. get cool 3. The _____ of pigs can be used to make glue. A. skin B. meat C. hair 4. The training of pigs is easier because _____. A. they are smarter than dogs and cats B. they can do everything easily C. they have a very good sense of smell 5. The underlined phrase 'sniff out' probably means _____ something by nose. A. smell B. discover C. feel