中文不像英文，采用固定的格式来表达时态，中文是用限定时间的实词和表示动作完成的虚词来指明时态的，甚至是用特定的语境来表达时态的。 比如说“我昨天看了场电影”，这里的“昨天”就是限定时间的实词，“了”就是表示动作完成的虚词。限定时间的词有很多，比如“去年”、“以前”、“曾经”等，表示动作完成的词则有“了”、“过”、“完”等。 又如，这本书是鲁迅写的，这句话中没有任何指明时态的词，但是我们看了都知道是以前写的，至少也是1936年以前。 所以说汉语不是用固定的格式来表达时态，要么用特定意思的词来指明，要么用语境来表达，只要意思正确，不会存在语法错误。

after the verb as the indication of result as a main word as crossing smth, passing smth or celebration smth

过 guo4 1. verb. means pass. ie: a.时间过得很快。 Time passes fast. b.过生日。 Celebrate birthday. 2. particle for a main verb in a word. ie: a.走过 pass over， b.穿过cross over， c.经过 experience/ pass a building on your way. 3. Completion Tense. Means the action has been completed. ie: a. 我去过泰国。I have been to Thailand. b. 我看过这部电影。 I have seen this moive. 4. Noun. Most of the time, 过 will combine with other character to become a word. a. 过失 mistake b. 过分 overly，beyond measure c. 过剩， too much/many You may feel most of the time, this character will connect with some thing beyond the limit or has been done （beyond the time/experience) If you are interested, I have a 200 hanzi program that explains all about Hanzi,meaning, way of using, conversation,and some history behind it. you can also pick up the hanzi, I will tailor make lesson for you including all above points. Also can combine with business related meeting/speech/ppt in Chinese. Thanks.

ur question is too BIG........ there is lots of 过....