以下哪条不是主动转运特征()
A.消耗能量
B.可与结构类似的物质发生竞争现象
C.由低浓度向高浓度转运
D.不需载体进行转运
E.有饱和状态
参考答案:D
WK-20型挖掘机底门阻尼装置由哪些部件组成?
A computer virus is a computer program that is created to make and spread (71) of itself.
A.programs
B.virus
C.copies
D.files