Question: Based on the air rocket experiment setup in the hall, assuming the floor of the launch pad is the origin $(0,0),$ the launch pad height is $n,$ the bottom of the recovery bucket is on the ground, $$ is the total flight time, $v_0$ is the initial velocity, and ${?}_g$ is the gravitational acceleration. Which of the following statements about the experiment setup and corresponding physical quantities is correct?

$($A$)$ The inclined placement of the PET bottle indicates that the launch angle $e$ has been set.

$($B$)$ The position of the PET bottle at launch time $t=0$ is $(x,y)=(0,n).$

$($C$)$ The maximum height above the ground during the flight of the PET bottle is $\frac{si{n}^{2}si{n}^2(0)}{2}.$

$($D$)$ The maximum horizontal displacement of the PET bottle during the launch process is $v_{0}cos()T.$