My uncle Tom can think on his feet.

我的汤姆叔叔能独立思考。

And he can think on his feet.

他可以独立思考。

He has to think on his feet because so many unexpected things happen in the restaurant.

餐馆里有那么多意想不到的事情发生，他必须迅速反应。

I think that Keir has found a new flex, a new ability to think on his feet.

我认为 Keir 找到了一种新的灵活性， 一种新的独立思考能力。