I. Aspect versus tense
Mandarin learners who are native speakers of an inflectional language, such as English, tend to mistake le 了for a past tense marker because it is often used in remarks related to past actions or situations. Meanwhile, le also puzzles them when sometimes it is absent from sentences where they expect it to be used. The following four examples all have a time word or expression indicating a past time, yet only two of them use le 了.
Le 了 is used.
1. Zuótiān wǒ mǎi-le sān běn shū.
I bought three books yesterday.
2. Shàng ge zhōumò wǒ qu
Le了is not used.
3. Zuótiān wǒ shì wǔ diǎnzhōng huílai de.
Yesterday it was at that I came back.
4. Yǐqián wǒ bú cháng yùndòng, suǒyǐ hěn pàng.
Before, I did not often exercise. So I was fat.
The last two examples above show that, even if the time words indicate the past, le is not used in either sentence. If le is not a past tense marker, what is it and how is it used? The discussion should begin with an understanding of the concepts of tense and aspect.
“The category of aspect is very different from that of tense: a marker of tense relates the time of the occurrence of the situation to the time that situation is brought up in speech. In English, for example, we have past tense, as in, ‘I proposed a toast’, where the suffix -ed signals that the act of proposing took place before the time of speaking. Mandarin has no markers of tense. The language does not use verb affixes to signal the relation between the time of the occurrence of the situation and the time that situation is brought up in speech. Aspect, on the other hand, refers, not to the time relation between a situation and the moment of its being mentioned in speech, but, rather, to how the situation itself is being viewed with respect to its own internal makeup.” (Charles N. Li and Sandra A. Thompson: 1981, p. 184).
Charles Li and Sandra Thompson point out that aspect expresses different ways of viewing a situation. While inflectional languages like English are concerned with marking the time of the action in relation to the time of the remark in which it is brought up, Chinese is more concerned with the developmental stage of an action. A time expression alone or even the context itself is sufficient to show time, such as the past, the present or the future. Therefore, inflection is not at all necessary and is non-existent in Chinese. In a given time frame, in Chinese an action is viewed with an emphasis on a particular phase along the course of its progress, which can be its beginning, its continuation, or its completion. “Each of these stages is referred to as an ‘aspect.’ A past action has all these aspects, so does a present action and a future action. Therefore, in English, the ‘perfective,’ or the ‘completive,’ may appear in the present tense, the past tense or the future tense.” (Hung-nin S. Cheung: 1994, p. 207).
Past perfect: I had already arrived (when he called).
Present perfect: I have already arrived.
Future perfect: I shall have arrived (by eight tomorrow morning).
(Hung-nin S. Cheung: 1994, p. 207).
Knowing the difference between aspect and tense makes it easier to understand that le 了marks the perfective aspect of an action, not past tense. There are two kinds of le 了that relate to completed actions. One is the perfective aspect particle le了, the other is the modal particle le了. Read on to learn their differences.