A:how many populations there are in the world
B:how much population there is in the world
C:how many the population of the world i
D:what the population of the world i
为了防止铁制品受腐蚀,下述采取的措施中错误的是( )
森林砍伐形成的裸地,在没有干扰的情况下的演替过程是( )