複選題

28. A solid nonconducting sphere of radius R = 5.6 cm has a nonuniform charge distribution of volume charge density ρ = (14.1 pC/m³)r/R, where r is radial distance from the sphere's center.
(A)The shell theorem cannot be applied in this case.
(B)The sphere's total charge is 7.78×10⁻¹³ C.
(C)The magnitude of the electric field at r = 0 is zero.
(D)The magnitude of the electric field at r = R/2 is 5.58×10⁻³ N/C.
(E)The magnitude of the electric field at r = R is 1.12×10⁻² N/C.