A:planted
B:will plant
C:were planted
D:will be planted
已知f1(x)=sinx+cosx,记f2(x)=f1′(x),f3(x)=f2′(x)fn(x)=fn﹣1′(x)(n∈N*,n≥2),f1π4+f2π4+f3π4+f2013π4=( )
下列现象中,与地球自转有关的是( )