When we study Chinese, we are confused between 过guo and 了le. The aspect particle 过 (guo) is used to indicate that an action has been experienced in the past.
Basic Pattern
What this expresses is that the verb has been done at least once before, without specifying a particular time. 过 is used to talk about whether something has ever happened - whether it has been experienced.
Examples
Some examples of how 过 is typically used:
我 去 过 中国。I have been to China.
你 看 过 那 个 人 吗?Have you seen that person?
Negating a 过 sentence
Because 过 is used to talk about past actions, it should be negated with 没. The structure is:
Examples:
我 没 去 过 中国。I have not been to China.
Using 过 with 了
You'll sometimes see 过 used together with 了. This can be a little confusing, as it doesn't seeing to be following the rules laid out above. For more on this special usage of 过, see the article on using 过 with 了.