—Me too. I especially like the _______ written by J.K.Rowling.
A:homework
B:numbers
C:movies
D:books
已知函数f(x)=x+1,x≤0log2x,x>0,若方程f(x)=a(a∈R)有四个不同的解x1,x2,x3,x4,且x1<x2<x3<x4,则(x1+x2)x4的取值范围是____
如图,长方体ABCD﹣A1B1C1D1中,AA1=AB=2,AD=1,E,F,G分别是DD1,AB,CC1的中点,则异面直线A1E与GF所成角为( )