Plot the points with polar coordinates $(-5,\frac{2\pi }{3})$ and $(2,-\frac{11\pi }{6})$ using the pencil.

Step 1 ：Given two points with polar coordinates $(-5,\frac{2\pi }{3})$ and $(2,-\frac{11\pi }{6})$.

Step 2 ：The polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction.

Step 3 ：The polar coordinates can be converted to Cartesian coordinates using the following formulas: $x=r\cos (\theta )$ and $y=r\sin (\theta )$.

Step 4 ：Convert the given polar coordinates to Cartesian coordinates.

Step 5 ：For the first point $(-5,\frac{2\pi }{3})$, the Cartesian coordinates are approximately $(2.5,-4.33)$.

Step 6 ：For the second point $(2,-\frac{11\pi }{6})$, the Cartesian coordinates are approximately $(1.73,1)$.

Step 7 ：$\boxed{{\displaystyle \text{Final Answer: The points with polar coordinates }(-5,\frac{2\pi }{3})\text{ and }(2,-\frac{11\pi }{6})\text{ are plotted on the Cartesian plane. The first point is located in the second quadrant with Cartesian coordinates approximately }(2.5,-4.33)\text{, and the second point is located in the first quadrant with Cartesian coordinates approximately }(1.73,1).}}$