Two streamlines cannot cross each other. Why ?

For a stream line flow of water following statements are given below (a) Two streamlines do not intersect each other. (b) streamlines must be straight. (c ) streamlines flow is more likely for liquids with low density and height viscosity. (d) streamlines flow is more likely for liquids with high density and low viscosity.

Can two stramlines cross each other in a flowing liquid ? Explain.

Two gases cannot diffuse into each other.

(a) An electrostaic field line is a continous courve. That is a field line cannot have sudden breaks. Why not ? (b) explain why two filed lines never cross each other at any point.