What is the slope of the displacement $-$ time graph when the body has uniform motion?

The velocity$-$time graph of a body has a negative slope. The body is undergoing

What conclusion can you draw from the displacement$-$time graph of a body as shown below?

What do you understand by the displacement-time graph? Draw a displacement-time graph for a girl going to school with uniform velocity. How can we calculate the uniform velocity from it?

If the displacement-time graph for a particle is parallel to the displacement axis,what is the velocity of the particle?

The graph given below is the distance-time graph of an object.
$(i)$ Find the speed of the object during the first four seconds of its journey.
(ii) How long was it stationary?
(iii) Does it represent a real situation? Justify your answer.