試題詳解

2.Which of the following statements is not correct?
(A) A curl-less vector field can be expressed as the gradient of a scalar field.
(B) A divergence-less vector field can be expressed as the curl of a vector feld.
(C) A curl-lJess and divergence-less vector field is a constant vector field.
(D) A smooth and rapidly decaying vector field can be expressed as the sum of a curl-less vector field and a divergence-less vector field.