These sentences refer to future time, but lái is not a future-tense form. Strictly speaking, Chinese verbs do not have tenses. The same form of the verb can be used in present, past, and future contexts.

We translated the sentence Tā zài Táinán gōngzuò. as "He works in Tainan" assuming a present context. But in a past context we could translate It as "He worked in Tainan; and in a future context we could translate it as "He will work in Tainan." The verb form gōngzuò does not tell you what time is being talked about. You have to look elsewhere for that information, perhaps to a time expression like "last year" or "now" or "tomorrow," or to the conversational setting.

Aspect: Le is an aspect marker. Through the use of and other one-syllable markers (de, zhe, ne, guo), the Chinese language indicates whether the occurrence being talked about is completed, ongoing, about to occur, or experienced for the first time. Aspect markers may also be used to indicate whether the whole situation in the sentence is a new, changed situation.

"Completion" and "new situation" are not tenses but aspects. Aspect is a way of talking about events or activities in relation to time. While tenses categorize action in terms of features such as completeness and change. Aspect markers are very different from tense markers because the same aspect may be used in past, present, and future contexts. We may speak of an action that will be completed as of a future time, for example, or of a situation that was new as of a past time. English communicates these ideas to a certain extent through the use of many different tenses for the verb (future perfect, simple past, etc,). Chinese does this through the use of aspect markers and time words. The verbs themselves do not change form.

Le is used in exchange 2 to indicate two aspects-completion and new situation, (it is, however, often used to indicate only one aspect.)

Here, it indicates that the person has come, meaning that the action is completed, and that the person is now here, a changed situation. When the marker le refers to both these aspects, we call it "combined le." Combined le can be thought of as a telescoping of the completion le followed by a new-situation le: le le becomes le. In the next two units, you will see the marker le used to Indicate each of these aspects separately.

Negative of combined le: Compare these affirmative and negative forms:

Notice that the marker le does not appear in the negative answer in the exchange.

Hái: The negative of a sentence containing combined le_ will include the adverb hái, "yet," as well as the negative méi(you). In English, the "yet" is frequently left out.

Like other adverbs such as yě, hái always precedes the verb, although not always directly. Elements such as the negatives and méi may come between an adverb and a verb,

Méiyou, "not have" is used to negate the aspect of completion; that is, to say that a certain event did not take place. Méiyou may be shortened to méi. Here are three possible negative answers to the question.

Tā lái le ma? "Has he come?"

Position of time words: Time phrases occupy the same position in a sentence as adverbs such as yě and hái between the subject and the verb.

(shì)...de: ^[5] This is another way to indicate the aspect of completion. The aspect marker le and the pattern (shì...de) perform different functions and convey different meanings. This is how they are different:

The aspect marker le or its negative méi (you) is used when the center of interest is whether or not an action took place. For example, if you do not know whether Mr. Sun came or not, you would ask:

and you would be answered either

or

In this question and answer, you use le or its negative méi(you) because the focus is on whether the action took place or not.

The purpose of the (shì)...de construction, on the other hand, is to focus on additional information about a completed action; that is, the construction is used when the center of interest is NOT whether or not a certain action took place.

For example, once it has been established that Mr. Sun did in fact come, the (shì)...de construction will probably be used for any additional questions and answers about his coming. For example:

These questions and answers use the (shì)...de construction because you already know that Mr. Sun came and now you are asking for additional information about his visit. Many types of additional information can be focus points for which the (shì)...de construction is used.

In Tā shi shénme shíhou láide? the additional information is the time when something happens.

In Tā shi yíge rén láide ma? the information asked for is the manner in which something takes place.

Other possible focus points are place, cause of action, goal of action, and performer of action.

Now let's take a look at how shì and de function separately in this construction. The verb shì, coming before the phrase which is the center of interest, serves as a signal that what follows is emphasised. The verb "to "be" is often used in a similar way in English to mark the center of interest:

Another way of showing the center of interest in English is by word stress. Here is a comparison between focusing in Chinese with (shì)...de and focusing in English with stress:

The marker de coming after the verb indicates completion. When the marker de is not used in the sentence, that sentence no longer describes a completed event. The marker shì by itself emphasizes something about the action.

Compare these sentences:

For the time being, you will not use shì without de.

The negative form of the (shì)...de construction is bú shi...de . Compare this with the negatives you have already learned:

Notice that in a (shì)...de construction the negative bú precedes the verb shì rather than the main verb. Short answers are also formed with shì rather than with the main verb:

The (shì)...de construction is not used in every completed-action sentence containing a time, place, or manner phrase. If the center of interest is still whether or not the action took place, le is used. If, for example, you knew that someone was expected to come yesterday and you wanted to find out only whether he actually did come, the conversation might go as follows:

Literally, yíge rén means "one person." When the expression is used to describe how someone does something, translate it as "alone"

The word for "day" is the bound word -tiān. To ask "what day" (literally "which day"), the bound word něi- "which," is combined with the bound word -tiān, "day": něitiān (like něiguó, "which country").

Some speakers say the -tiān in these words in the Neutral tone: qiántian,zuótian, jīntian, míngtian, hòutian.