a concrete instance的用法和样例：
- It is sh owed through a concrete instance that the method is simple, quick and accurate.
- Adduce a concrete instance , let others participate in the process that you improve, you are able to get bigger stimulating and courage.
- The word "apple" is a concrete noun.
- A concrete wall is built to stop silt from leaking to the conservation land.
- What does this mean for us in a concrete manner?