The boundary condition of the electric field intensity of steady electric fields is A: the normal components are continuous. B: the tangential component are continuous. C: if there is no current at the interface, the tangential components are continuous. D: both the tangential and normal components are continuous.

反映角膜表面每个点真实角膜曲率的图是 A: axial power B: tangential power C: refrative map D: elevation E: subtractive map

Which is false? A: Streamlines and equipotential surfaces are perpendicular everywhere. B: Streamlines point from the position with lower potential to the position with higher potential. C: Streamlines do not intersect. D: The tangential direction of the streamline is the direction of the electric field intensity at the point.

The<br/>magnetic field lines are used to visually describe the distribution<br/>of the magnetic field around the magnet. For the following<br/>statement,( <br/>) is wrong. A: Each<br/>magnetic field line is a closed loop curve B: No<br/>two magnetic field lines can cross each other C: The<br/>length of the magnetic field line reflects the strength of the<br/>magnetic field D: The<br/>tangential direction of any point on any of the magnetic lines is the<br/>direction of the magnetic field at that point