A central, and historically controversial, component of evolutionary theory is that all living organisms, from microscopic bacteria to plants, insects, birds, and mammals, share a common ancestor.
- controversial [ˌkɔntrəˈvə:ʃəl] adj.有争议的
- component [kəmˈpəunənt] n. 组成部分
- evolutionary [ˌi:vəˈlu:ʃənəri] adj.进化的
- organism [ˈɔ:ɡənizəm] n.有机物
- microscopic [ˌmaikrəsˈkɔpik] adj. 极微小的
- ancestor [ˈænsistə] n.祖先
