Please refer to the following codes. ACLS:SPSET 0,345:SPHOME 0,8,8:Y=120:VY=0 WHILE TRUE VSYNC 1:K=BUTTON(2) IF(K AND #A)!=0 THEN VY=-4 ELSE VY=VY+0.25 Y=Y+VY:SPOFS 0,200,Y,0 IF Y>=240 THEN Y=239:VY=-VY IF Y<=0 THEN Y=1:VY=-VY WEND