A.0
B.1
C.π
D.2π
[单选题]A.0B.1C.πD.2π
[单选题]A.5/6B.1/6C.1/3D.1/5
[单选题]A.B.C.D.
[单选题]A.导数存在,且有f′(a)=-lB.导数一定不存在C.f(a)为极大值D.f(a)为极小值