Can the distance travelled by a particle be zero when displacement is not zero?

$A$ particle accelerates from rest at a constant rate for some time and attains a constant velocity of $8\, m s^{-1}$. Afterwards,it decelerates at a constant rate and comes to rest. If the total time taken is $4\, s$,the distance travelled is:

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-life situation? Justify your answer.

What is meant by free fall? Two bodies,one of mass $1\,g$ and other of mass $1\,kg$,are dropped from the same height in a vacuum. Compare the two time intervals in which the two bodies will hit the ground.

Draw velocity-time graphs for the following situations:
$(i)$ When a body is moving with uniform velocity.
$(ii)$ When a body is moving with variable velocity,but uniform acceleration.
$(iii)$ When a body is moving with variable velocity,but uniform retardation.
$(iv)$ When a body is moving with variable velocity and variable acceleration.

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?