【正确答案】topic Two negative effects of roads on the environment are referred by the professor through showing two examples. example 1 First, the professor mentions that roads or highways can do harm to plants, because roads cut off water resource of plants and thus force them to move to other areas for water. For example, a plant species called Yellow Star Thistle was forced to migrate to a new environment because of the effect of roads and competed with local plants over resources. example 2 Secondly, the professor points out that roads can also affect animals. For example, Kit-foxes hunt for mice or squirrels as their food. They worry about crossing roads and hunt less food. So their number decrease because of the lack of food resource.

【答案解析】[听力原文] M: Roads like highways help connect people from one place to another; however, roads have two negative impacts on the environment by affecting both plants and animals living in the local area. Firstly, highways or country roads affect native plants by cutting off water sources and thus force them to migrate to other areas for water. A plant species such as Yellow Star Thistle that invades or takes over the area can potentially cause harm to the other native plants. These alien plants are so aggressive that they even kill off populations of native plants all together in the competition over resources. Roads can also affect animals' lives by blocking their territories and keeping them away from food and water, because crossing the road to follow food source could be very dangerous because of the passing vehicles. In other words, modern roads act as dangerous walls for many animal species and break their supply lines in the area. For example, kit foxes hunt small species like mice or squirrels to survive, but if there is a road in the Kit foxes' path towards their food source, the foxes will starve to death and thus decreasing the number of the species in the area.