抓老鼠的英语表达是 Catch the mouse。这个短语可以直接用来描述捉老鼠的动作，其中 "mouse" 可以是单数或复数形式，具体取决于上下文。例如：

1. The cat caught the mouse.

2. They are trying to catch the mice in the barn.

3. It's important to know how to catch mice without harming them.