did they see the aliens （play）football just now 应该填什么形式
问题描述：
did they see the aliens （play）football just now 应该填什么形式
答
playing
答
were playing
答
play
因为just now 是刚才 而且助词是did
是看了个过程
playing则是正在过程中
theyve been seeing the aliens playing football for a while