循环tag @e[type=snowball] remove a
链execute @e[type=snowball] ~~~ detect @s ~~~0.1 air 0 detect @s ~~~-0.1 air 0 detect @s ~~0.1~ air 0 detect @s ~~-0.1~ air 0 detect @s ~0.1~~ air 0 detect @s ~-0.1~~ air 0 tag @s add a
如果雪球没有标签A,就是落地了。但是检测雪球落地的命令方块要在上面两个命令方块之后