we see the old man ___a walk along the river at the moment用take的什么形式?原因是什么?

问题描述:

we see the old man ___a walk along the river at the moment
用take的什么形式?原因是什么?

taking

taking
see sb doing

taking
see sb doing 看见某人在做某事;强调动作的进行;
题意:我们刚才看到那位老人在沿着河边散步.