A:more than the length twice
B:twice more than the length
C:more than twice the length
D:more twice than the length
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设函数f(x)在x=1处可导,则lim△x→∞f1+△x-f1-2△x等于( )
“美人鱼”的学名叫儒艮,之所以被人们称为“美人鱼”,是因为母兽给幼崽喂奶时常浮出水面,像人类哺乳的情形.你认为“美人鱼”属于( )