The man is looking_____his child_____the playground_____the moment.

for on for

The man is looking for his child on the playground at the moment.
意为：那个人此时在操场上寻找自己的孩子。
第一个空虽然填after也符合语法，但就变成在操场上照顾孩子，个人觉得“寻找”更为贴切

look after 照看
on 在..上
at the moment 此刻

after; on; at

for on at

at
on
in