绿藻门含有叶绿素()光合色素。
A.a,b
B.a,d
C.a,c
D.a,e
参考答案:A
Characteristics of monopolistic competition include all of the following EXCEPT:()
A. differentiated products.
B. high barriers to entry.
C. large numbers of independent sellers.
教育目的是()
A.教育行动的先导
B.贯穿于整个教育活动的始终
C.只在教育活动开始时发挥作用
D.确定教育内容,选择教育方法的依据