A:C2H4、C3H8
B:CH4、C5H8
C:CH4、C4H8
D:C2H6、C3H8
— _________ book?
— The one on your desk.
— It's Tom's
下列说法正确的是( )
设0<α<π2,a是大于0的常数,函数F(α)=1cosα+a1-cosα,若F(α)≥16恒成立,则a的取值范围是( )