a very poor swimmer的用法和样例：
- No,I'm a very poor swimmer,I can swim in a swim pool but I don't think I can do so in the sea.
- It is a very poor photocopy but you should be able to make something of it.
- He made a very poor witness for himself.
- That man has a very poor memory.
- Wood is a very poor conductor of heat.
- Our table was in a very poor position.