The migration of pronghorns 　　Pronghorns rely on their eyesight and 23 ________　to avoid predators. One particular population’s summer habitat is a national park, and their winter home is on the 24 ________. where they go to avoid the danger presented by the snow at that time of year. However, their route between these two areas contains three　25 ________. One problem is the construction of new homes in a narrow 26 ________　of land on the pronghorns’ route. (请填24题答案）