Tense and use of 了

Question

I struggle a bit to get my head around tense in Mandarin, and in particular when I need to use 了 (le).

Do you have any tips, examples or resources to help me out with this?

Answer 1

Usually 了 is used to indicate past tense (or the completion of). Such as:

我吃了

了 is added to the end of the sentence that change the statement to past tense. You can add 过 before 了 to add emphasis.

E.g., 我吃了 (I ate) vs. 我吃过了 (I have (already) eaten.)

but 了 may be used for different reasons, some of which have nothing to do with past tense.

With imperatives, it adds urgency:

走了, 走了

(Let's) go, (let's) go.

So, a negative imperative becomes a warning:

别说话

(Keep quiet.)

vs.

别说话了

(I'm warning you [to]) stop talking!

With certain modifiers you can use 了 to indicate future tense:

天就要下雨了（it's raining soon)

Here 要 (an auxiliary verb) indicates future tense, by implying the sense of "going to do (something)." 會 is another auxiliary verb that does the same thing, but in the sense of "intending to do (something)."

了 when used after an adjective or noun, conveys the meaning "has become"

我餓 (I'm hungry)

vs.

我餓了 (I became hungry)

Here 了 expresses a clear (change of) state.

了 can also be used to express excessiveness.

太 + (stative verb/adjective/noun) + 了. E.g., 太冷了.

(stative verb/adjective/noun) + 极了. E.g., 热极了.

可 + (stative verb/adjective/noun) + 了. E.g., 可难了.

太 can be used without 了. If omitted, the tone can sound rather rough.

Answer 2

The particle 了 (le) suggests a completed action. For example,

Chi fan le, finished eating.