In English prepositions are often used to illustrate location broadly defined – relative to some other object (on the table), in time (at the end of the week), in a logical sequence (from this we can see), and other placements too numerous to mention. (I have long thought that prepositions are the most annoying feature of English for students of that language. Why is it “in the night city of time”? Why am I “in the house” but “at home”? Why is “of example” wrong, but “by way of example” is correct?)
And Chinese has a Word type called jiècí (介词), but what native English speakers would consider prepositions are only a part of that category.
Here I want to focus on one 介词, zài 在, and to try to encourage the reader to think of it as a comprehensive way of saying “to be located.”
The most obvious example is from a dialogue like “Where is that book?” “On the table.” In Chinese this would be
那本书在哪里？(Nà běn shū zài nǎlǐ?)
在桌子的上面。(Zài zhuōzi de shàngmiàn.) (Often native speakers just limit this to 在桌子上. Zhuōzi means “table.”)
Here 在 in the first sentence just translates into English as “is located” and in the second as the relevant preposition, “on.”
More generally, the meaning of zài in the second sentence is “is located (plus preposition),”
and in this English sentence the preposition to be used is on the table. So, the book is located on the table (桌子的上面,zhuōzi de shàngmiàn).
Note here that Chinese has its own words for above/on top of/over (上面, shàngmiàn), under/beneath (下面, xiàmiàn) and a host of others. Chinese thus distinguishes locations in space somewhat like English does.
But it is “location” in time that is most interesting. Often when in English one wants to indicate that the speaker is in the process of doing something, it uses the present participle, i.e. the “ing” ending. “What are you doing?” “I’m reading a book.” Chinese would render those two sentences this way:
你在做什么？(Nǐ zài zuò shénme?)
我在看书。(Wǒ zài kànshū.)
在 here doesn’t indicate location…and yet it does. In the timeline of this person’s life, right now he’s “located” at or in the action of reading a book. Note that zhèng (正) can also sometimes be used as a substitute or inserted before 在, although to me 正 has always had the extra connotation of “exactly.” So these four sentences are all fine:
1. 我在看书。(Wǒ zài kànshū.)
2. 我正看书呢。(Wǒ zhèng kànshū ne.)
3. 我正在看书。(Wǒ zhèngzài kànshū.)
4. 我看书呢。(Wǒ kànshū ne.)
Note that when 正 is used there must be a ne(呢) at the end.
Yet I have long felt there are some subtleties. For starters, while all of them are grammatically correct, there are regional differences. For example, sentence 4 is generally used on the mainland and not in Taiwan. In addition, to me as a student, sentence 2 sounds a little peculiar, but still as I understand it there’s nothing wrong with it. Nonetheless, my impression after many years doing this is given a choice between sentence 1 and sentence 2, Chinese will generally choose sentence 1. (Perhaps because of the general preference for two-character words.) And sentence 3 has the connotation of reading a book being exactly what I am doing right now, as if I had planned all day to read a book now, or if I am explicitly choosing to read a book because I have to finish it soon, or I explicitly chose to read a book instead of some other activity, or some other reason. A good English approximation here might be the prepositional phrase “I am right in the middle of reading a book,” or “I am reading a book just now,” as opposed to merely “I am reading a book.”
This idea of (正) 在 as meaning to be currently located in some particular location in space or time is reinforced by the word for “exist” being 存在 (cúnzài) — 这个不存在！(This doesn’t exist!)
The English present participle in different circumstances is translated simply by adding 着 (zhe) to a verb. But be careful! I still remember the sentence from my textbook when I was just starting to study Chinese to illustrate the usage of this word — “There is a painting hanging on the wall.” While here the English sentence includes the participle “hanging” (although of course any time a painting is on the wall it is probably hanging there), it would be wrong to use any of the three forms above. While many Chinese teachers say the difference between 着 and (正)在 is the difference between an action and a state, I never find that definition entirely helpful, because I always think that saying “I am in the state of reading a book“ is a reasonable idea in English. The “ing” ending can express an ongoing state at any point in time (I am playing/was playing/at that time will be playing basketball) and what you wish to emphasize is happening right now (The stock market is crashing this afternoon.) So for Chinese to so meticulously separate 着 and (正)在 doesn’t really ring true with me.
And after, um, extensive discussions with Chén lǎoshī (not to mention with numerous Chinese teachers in years past) I think I have a handle on it. 正, 在 and 正在 forms are used to describe a process with a definite beginning and an end, and the time location is between those two pnts. In addition, with these forms the emphasis is on the action — I am playing tennis and not eating lunch. With 着, in contrast, the emphasis is that the something — an action or a state — is ongoing. In English, both are implied with ing.
So with that said, the following are all correct:
“Xiao Li is eating now.”
“Xiao Li is eating at this moment/just now.” Note that here either 正 or 在 can be dropped, but if so to have this meaning there must be a ne (呢) at the end, and further it is OK to use 正 and 在 and add the 呢. The addition of this word provides the emphasis of “just now,” and allows the dropping of 正 or 在. And if 正 and 在 are both retained, the 呢 is not necessary, but adding it does no harm.
In English this would still be “Xiao Li is eating at this moment/just now,” but in Chinese to emphasize continuity they add 着. In English this distinction isn’t common; perhaps one could say “Xiao Li is still eating/hasn’t finished eating/is continuing to eat,” but I think that one wouldn’t say these English sentences unless one meant “Xiao Li is taking longer than expected to finish eating,” which is not what this Chinese sentence means.
While you can imagine construction with 着 eventually ending, it is not the emphasis. “I am thinking of you” is an action that in the English way of thinking will (presumably) end at some point, maybe when I get hungry or sleepy. But whether you want to say 我想着你 (Wǒ xiǎngzhe nǐ) or 我正在想你 (Wǒ zhèngzài xiǎng nǐ) depends on whether you want to emphasize the action part (我正在想你) or the ongoing part, or the fact that I am thinking about you and will continue to do for some undetermined amount of time (我想着你).
In addition, often 着 without（正）在 will be used when you want to emphasize being in that state in combination with another state. If Chinese had country music, for example one could write “I am/was drinking, and thinking about you” as (我喝着酒，想着你, Wǒ hēzhe jiǔ, xiǎngzhe nǐ).” Because the emphasis is on the state and not being in the middle of a process with a defined beginning and end, in literature and song lyrics often sees 着.
Unfortunately, the character着 can be read multiple ways – I am familiar with zhāo, zháo, zhuó and zhù. Naturally, pronounced in these different ways, the character has different meanings. But that is a problem for another day.