One of my colleagues, a native Chinese speaker, asked me whether I was still learning Mandarin Chinese. I told him that I had given up. He was baffled by this.
"But Chinese is such a simple language. It has no grammar!"
Now of course, Mandarin has a grammar, because every language has a grammar.
This is one of the curses of being a native speaker of a language: You don't even realize how hard your language is. As far as you're concerned, your native language is as easy as falling off a log.¹
Now, it's true that Mandarin has almost no inflections, unlike most European languages. But that's not the same as saying it has no grammar. It's just that the grammar moves from being internal (inflection) to external (helping words and word order).
Sidebar: David from Popehat lays out some of the simplifications, but I think he oversimplifies the use of the completion marker 了. It's not strictly speaking a past-tense marker, at least not in the sense we consider it in English. Proper use of 了 is more complicated, and this page tries to explain some of the subtleties. David later tries to explain Mandarin phonology. I must admit that I have an advantage in already having a tonal language wired into my brain, so I don't have the hurdle of learning to hear and speak tones. I just have to learn to hear and speak different tones. Which is still frustrating. End sidebar
One of the consequences of "your own native language is simple" is that native speakers are sometimes the worst choices for explaining their own language, since they simply fail to recognize how weird their language is. An example I gave some time ago was that elusive third tone. If you ask a native speaker how it is pronounced, they will say one thing ("dipping tone"), but then when they themselves speak the third tone they do something completely different ("low level tone"). Native speakers are so convinced that the third tone dips that when you call them on it, they insist that the tone dipped, when in fact it barely moved at all.
That conversation with my father went something like this.
Me: "In that sentence, you said 〈low level tone〉."
My father: "No, I didn't. I said 〈dipping tone〉."
Me: "Well, sure, that time you said 〈dipping tone〉. But in the original sentence, you said 〈low level tone〉."
My father: "No, I didn't. Listen again. 〈repeats sentence and uses low level tone〉."
Me: "There, see? You used 〈low level tone〉."
My father: "No, I didn't. Here, you repeat back to me what you think I said."
Me: "〈says sentence with low level tone〉."
My father: "There, you got it!"
Me: "But I used the wrong tone! I should have said, 〈says sentence with dipping tone〉."
My father: "No, that's wrong. You exaggerated the tone too much."
That last remark from my father was what made it click for me: The low level tone and the dipping tone are complementary allophones. (My father, of course, has no idea what a complementary allophone is, but that's okay.)
Another example of native speakers not seeing the complexity in their own language is the use of the negative adverb 没. Mandarin has two main adverbs that mean "not": 不 and 没. If you ask a native speaker, they will tell you, "It's very simple. 不 is the general-purpose negation, and 没 is used only to negate the verb to have. In other words, 没 is always followed by 有." But then you will see that native speakers use 没 to negate all sorts of things that aren't 有. If you point this out, they will retcon it by saying that the phrase 没關係 ("no connection", which is an idiom that means "it doesn't matter, don't worry about it") is really a shorthand for 没有關係 ("doesn't have a connection"). Native speakers play this card whenever an out-of-place 没 shows up. "Oh, it's negating an invisible 有." If you ask them how to tell when there is an invisible 有 in a sentence, they will say "You just have to know," or sometimes the circular "Stick a 没 in front and see if it makes sense."
Sidebar: Here's a page that tries to explain the difference between 不 and 没. The way I internalize it based on limited observation is to say that 不 is not tied to a moment in time (innate or habitual property), whereas 没 refers to a particular incident (momentary property).
doesn't get wet
(he has an umbrella)
doesn't drink milk
(he's lactose intolerant)
isn't drinking milk
(he chose water)
This is similar to the distinction between English simple ("I do") and progressive ("I am doing"). Furthermore, 没 carries a sense of "yet"; you are denying that something is true now, but expecting that to change in the future. End sidebar
One downside about having such a superficially simple grammar is that it makes the language much more ambiguous. The more complex grammar of European languages acts as a checksum. If I say, "He are coming," then you know that something went wrong. The grammatical doodads act like signposts to confirm that you the listener are parsing the sentence correctly. It's like the road sign after every highway exit that reassures you, "You are still on Highway 405 Northbound." One of my colleagues told me that he missed those signs on his trip to Italy. There would be signs labeling each exit, but rarely was there a sign telling you what highway you were currently on!
To me, Chinese is difficult to learn because of its lack of guideposts that help steer you onto the right track. Without them, many sentences end up ambiguous. (In that example, the lack of any grammatical particle that distinguishes imperative from declarative mood led to the confusion.) The relative scarcity of grammatical particles makes me feel like I'm talking baby-talk. "Me want eat cookie."²
Resolving ambiguity is made even harder by the fact that every word in Mandarin has about a dozen homophones (fortunately, most of them not used in everyday speech), so you aren't even sure what word you're dealing with at the moment you hear it. You just know it's one of these two or three, and you have to wait and see which one actually makes sense when combined with the other words in the sentence (some of which may themselves also be ambiguous).
Adding to the ambiguity is that in many cases, you can omit words from a sentence if they are implied from context. So you now have to juggle the ambiguous mapping of sounds to words, the ambiguous grammatical context of those words (was that a statement or a direct order?), and choosing which implied words to insert to support your conclusion! Of course, native speakers can resolve all of these ambiguities very quickly, having been doing so since birth, and they are much better at picking up other cues (such as where the speaker speeds up and slows down) to help steer toward the correct interpretation. Indeed, in the language I learned as a young child, I can resolve these ambiguities with no difficulty at all.
Sidebar: Even native speakers sometimes have to go into explicit ambiguity-resolution mode by adding clarifying context. This happens in English occasionally: You might say, "He had a bat (the animal)" because the shorter sentence "He had a bat" would be ambiguous. Did he have an animal or an instrument for striking? End sidebar
One thing I do like to quibble about is the treatment of classifiers in Mandarin. Most people treat them as a quirk of the language, making them sound like an oddball feature that doesn't exist in European languages. An analogue in English would be the word "pair" when applied to scissors or pants. You can't say "a scissors" or "a pants"; you have to say "a pair of scissors" or "a pair of pants." (Particularly confusing because a "pair" of scissors or pants is still one article.) In Mandarin, every noun has a corresponding classifier.
You can think of classifiers as the Mandarin version of grammatical gender. The nouns in the language fall into around 170 different categories, and you just have to know which category word goes with each noun. There are patterns that help the learning process, but there are always exceptions that you simply must memorize.
For example, 条 is generally used for long, thin, flexible things, like a fish or a ribbon. But you also use it for dogs. Oh, and also for skirts and dresses. Go figure.
So the next time a native Mandarin speaker complains that English has all these arbitrary rules that serve no purpose other than making the language harder to learn, just ask them about classifiers. (They will naturally defend classifiers by saying that they are completely obvious and in no way arbitrary.)
Anyway, the bit about classifiers explains why the subway ticket vending machine asks you how many "sheets" you want: In Mandarin, it is very common to omit the noun and use only the classifier when the noun is implied from context. This happens in English, too. If you are a shop that repairs scissors, the clerk might ask, "What's wrong with this pair?" as shorthand for "What's wrong with this pair of scissors?"
The classifier word for ticket is 張 which translates as sheet. The full question is "How many sheets of tickets?" But since you are at a ticket vending machine, the noun is implied from context, and the shorter sentence "How many sheets?" is used instead.
¹ This natural tendency to think of what you do as normal reveals itself in the words that the Chinese language uses to refer to itself. The name for the country of China is 中國, which translates as the middle kingdom, because by an amazing coincidence, China happens to be right in the middle of the map. And the name for the language itself is 普通話, which translates as normal speech, because we all talk normally; it's the foreigners who talk funny by using their own words for everything.³
² In practice, the distinction between baby-talk and adult-talk in Chinese is accomplished in two ways. First, babies have a specialized vocabulary: babies say doggy instead of dog, for example. Second, adults employ modal particles which convey the attitude of the speaker. Cantonese is notorious for having a large number of these sorts of particles. I don't know most of them, so my speech tends to come off as rather rude and abrupt.
³ Someone said that a neighbor of his grandmother complained, "I don't understand why people in foreign countries bother to learn a second language. Why don't they just talk normal?"