The displacement-time graph of a body is parallel to the time axis. What will you infer about the velocity of the body?

$A$ body moving with uniform acceleration has velocities $20 \, m/s$ and $30 \, m/s$ when passing two points $A$ and $B$. Then the velocity midway between $A$ and $B$ is:

What is the nature of motion of a particle depicted by the following displacement-time graphs?

State whether the following statement is true or false:
In one-dimensional motion,the average velocity and the instantaneous velocity are unequal.

$A$ body can have zero average velocity but not zero average speed. Justify this statement by giving an example.

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.