No Chinese tense~~but some word means past!

None. In fact, there are no tenses in Chinese. And verbs never change their form.

http://en.wikipedia.org/wiki/Synthetic_language#Very_isolating Chinese is an analytic language. It's on the very isolating end of the morphological scale amongst all the world languages. There are no plurals, tenses, gender, or any type of conjugations whatsoever. Everything is formed combinatorially.

It's complicated. I'm investigating it just now. Verbs don't change their form, but they use various combinations of particles (guo and le) in various different patterns to express what in English are past tenses. In chinese, it's very important to be able to specify time, so you need to concentrate a lot on placing actions in timeframes. Once you can say all your 'ago, since, for, previously, after, still, anymore' you're already at 75%.

There are some words used to express past tense in Chinese, they follow the verb,otherwise there are no other tenses. Those words are : 过 guo (experienced action marker) expressing something that passed. 了 le modal particle intensifying preceding clause,also called (completed action marker) Notice: That is one of the usages of "le" 了 and "guo"过