根据神经纤维直径粗细及来源,将传人纤维分为
A.A类B.B类C.A、B、C三类D.Ⅰ、Ⅱ、Ⅲ、Ⅳ四类
参考答案:D
函数f(x)=(x-2)2,则f′(1)=( )
A.-2
B.2
C.1
D.-1
—It _____ Yang Liwei about 21 hours _____ around the earth 14 times in the spaceship.
—How great he is! [ ]
A. spent, moving
B. took, traveling
C. took, to move
D. spent, to travel