That's not what I mean. 那不是我想表达的。

　　I'm not sure (I don't know) what you mean. 我不太确定你在说什么。

　　I need to focus on this. You know what I mean? 我得专注于这件事，你知道我是什么意思吗？

　　See what I mean? 知道我是什么意思？

　　Do you think he's cruel? 你觉得他很残忍吗？

　　That's not what I meant. I think he's selfish.  我不是那个意思。我觉得他有点自私。