许多动物在夜间保持清醒以躲避人类

mammal– n. an animal that feeds milk to its young and that usually has hair or fur covering most of its skin

vigilant– adj.carefully noticing problems or signs of danger

hike– v. to walk a long distance, especially for pleasure or exercise

trace – n.a very small amount of something

consequence– n.something that happens as a result of a particular action or set of conditions

species– n. a group of animals or plants that are similar and can produce young animals or plants

scary– adj. causing fear