Learn Hardcore Chinese: wǒ yǒu liù běn shū.

本 (běn) is the measure word specifically for bound printed materials, like books, magazines, notebooks.
So the structure is:
我 + 有 + 六 + 本 + 书
subject + have + number + measure word + noun

You cannot say 六书; it must be 六本书 (six books), just like English needs “a piece of paper” rather than “a paper” in some contexts. In Mandarin this rule is much stricter and applies to almost all countable nouns.

Could I use 个 (gè) instead of 本 (běn) and say 六个书?

Normally, no.

个 (gè) is a very common, general measure word, but it does not work well with 书 (shū, books).
Native speakers say 一本书 / 两本书 / 六本书, not 一个书 / 六个书.

In very casual speech, people sometimes overuse 个 (gè) with things where it “shouldn’t” go, but 六个书 still sounds clearly incorrect or childish. Use 本 with books.

Why isn’t there a word like “are” or “do” in the sentence? English says “I have six books” or “Do you have six books?”

In this sentence, 有 (yǒu) itself means “to have”, and Mandarin doesn’t need any extra helping verbs like “do.”

English: I have six books.
Chinese: 我有六本书。 (literally: I have six CL book)

No separate word for “do,” and no extra verb like “are.”
To ask a yes‑no question, you usually just add 吗 (ma) at the end:

你有六本书吗？ – Do you have six books?

How do I negate this sentence? How do I say “I don’t have six books” or “I don’t have any books”?

To negate 有 (yǒu), you must use 没 (méi), not 不 (bù).

General “I don’t have any books.”
- 我没有书。 – I don’t have (any) books.
Specifically “I don’t have six books” (I have fewer or more than six):
- 我没有六本书。 – I don’t have six books.
  (Implies: the quantity “six” is not true.)

Key point: 不有 is (almost) never used. For possession, 有 → 没有 in the negative.

Why is there no plural ending on 书 (shū), like “books”? Why isn’t it 书们?

Chinese nouns normally do not change form for singular vs plural.

书 can mean “book” or “books” depending on context.
When you add a number and a measure word, plurality is already clear:
- 一本书 – one book
- 六本书 – six books

The suffix 们 (men) is mainly for:

pronouns: 我 → 我们 (I → we), 你 → 你们 (you → you all)
some human nouns: 同学们 (students), 朋友们 (friends)

You almost never put 们 on inanimate objects like 书 in everyday speech.

Can I drop 我 (wǒ) or 有 (yǒu)? For example, just say 有六本书?

Dropping 我 (wǒ):
Yes, if the subject is obvious from context, Mandarin often omits the pronoun.
- Someone asks: 你有几本书？ (How many books do you have?)
  You can answer: 有六本书。 (Have six books.) – meaning I have six books.
Dropping 有 (yǒu):
For possession, no. You must keep 有.
我六本书 is not a proper sentence meaning “I have six books.”

So:

[subject] + 有 + [number] + [measure] + [noun] is required for possession.

How do I make different questions from this sentence, like “Do you have six books?” and “How many books do you have?”

Do you have six books?
Just change the subject and add 吗 (ma):
- 你有六本书吗？
How many books do you have?
Use 几 (jǐ) (“how many”) with the measure word:
- 你有几本书？ – How many books do you have?
Do you have any books?
- 你有书吗？ – Do you have (any) books?

Why is it 有 (yǒu, to have) and not 是 (shì, to be)? Why can’t I say 我是六本书?

是 (shì) is the copula “to be” used to link two nouns or a noun and a noun-like phrase:
- 我是学生。 – I am a student.
- 这是书。 – This is a book.
有 (yǒu) is the verb “to have / there is / there are”:
- 我有六本书。 – I have six books.

You cannot say 我是六本书 for “I have six books”; that literally sounds like “I am six books,” which is nonsense.
Use 有 for possession.

Is there any special tone change in 我有六本书 when spoken naturally?

Yes, there is a common third‑tone sandhi:

Underlying tones:
我 (wǒ, 3rd) 有 (yǒu, 3rd) 六 (liù, 4th) 本 (běn, 3rd) 书 (shū, 1st)
Rule: when one third tone comes directly before another third tone, the first one is pronounced as a second tone.

So:

我有 is pronounced wó yǒu (2nd + 3rd), not wǒ yǒu (3rd + 3rd).
The rest stays the same: 六本书 (liù běn shū).

Spoken smoothly: wó yǒu liù běn shū.

What’s the difference between 我有六本书 and sentences like 桌子上有六本书?

Both use 有, but in slightly different ways:

我有六本书。
- Subject: 我 (I)
- Meaning: I own/possess six books.
  This is possession.
桌子上有六本书。
- Literally: On the table have six CL book.
- Natural English: There are six books on the table.
  Here, 有 expresses existence / presence in a location (桌子上 – on the table).

Patterns:

[person] + 有 + [object] → “X has Y.”
[place] + 有 + [object] → “There is/are Y in/at X.”

Can I change the word order to 六本书我有? Does that mean the same thing?

Yes, you can say 六本书我有, but the focus changes.

我有六本书。 – neutral: I have six books.
六本书我有。
- Feels like: “Six books, I have (them).”
- Often used in contrast:
  - 六本书我有，七本书我没有。
    Six books I have; seven (i.e., having seven) I don’t.

So:

我有六本书 is the normal, default way to say it.
六本书我有 is marked and usually used for emphasis or contrast.