细菌性痢疾不同于阿米巴痢疾的特点,以下哪项不是主要的()
A.血象白细胞数目增多
B.潜伏期短
C.镜下有红、白细胞和巨噬细胞
D.粪便培养痢疾杆菌阳性
E.以上都不是
参考答案:A
Jane _____ these families of chimps for many years and helped people understand how much they behave like humans.
A.had studied
B.studied
C.studies
D.has studied
生物的演化说明了什么问题?