(a) Electric line of force or field lines is the curve along which a small positive charge would tend to move when free to do so in an electric field.So, the field lines are continuous.The sudden breaks in field lines will show that the charge is not in continuous motion at that point and jump from one point to another point, which is not possible.

(b) The tangent to a line of force force at any point gives the direction of the electric field at that point and if two field lines crosses each other at any point then at the point of intersection there will be two tangents which shows two direction of electric field at that point, and at a point there is only one direction possible of electric field.

So, never two field lines cross each other.