题目

Florida farmer Lohfner doesn't like moths(蛾). They eat my vegetables, he complains. But Lohfner has a secret weapon in his fight against moths: pheromones (外激素). Lohfner uses traps that release a female moth pheromone that is very attractive to male moths. Lohfner says that his traps catch almost 100 moths a week. For these moths, following pheromones cause their death. Nevertheless, for other moths and many insects, life would not be possible without pheromones. For moths, pheromones are a matter of life and death. Moths have poor vision, and most cannot use sound to communi如图所示，日常生活或生产实践中使用的机械，能抽象为斜面的是(  )                A．汽车方向盘        B．桔槔            C．盘山公路        D．铁葫芦