A1
A-not-A questions
The second way Chinese asks a yes/no question, how it differs from 吗, what happens to two-syllable verbs, and why 有 breaks the pattern.
Chinese has a second way to ask a yes/no question: say the verb, negate it, and let the listener pick. It is the same question 吗 asks, built differently.
你去不去？
Nǐ qù bú qù?
Are you going?
你是不是中国人？
Nǐ shì bú shì Zhōngguó rén?
Are you Chinese?
Adjectives work the same way, because an adjective is a verb.
今天冷不冷？
Jīntiān lěng bu lěng?
Is it cold today?
Two-syllable verbs can shorten
With a two-syllable verb, the full form is correct and the shortened one — first syllable, 不, whole verb — is what people usually say.
你喜欢不喜欢咖啡？
Nǐ xǐhuan bù xǐhuan kāfēi?
Do you like coffee?
你喜不喜欢咖啡？
Nǐ xǐ bù xǐhuan kāfēi?
Do you like coffee?
Both are natural. The short form is quicker and slightly more casual; neither is wrong.
有 uses 没, not 不
有 is the one verb that never takes 不, in this pattern or any other. Its negative is 没有, so the question is 有没有.
你有没有时间？
Nǐ yǒu méiyǒu shíjiān?
Do you have time?
你有不有时间？
你有没有时间？
有 is negated by 没 in every context, with no exceptions worth learning as a beginner.
Never with 吗
吗 and A-not-A are two ways of doing one job. Using both marks the sentence twice.
你去不去吗？
你去不去？
Pick one. 你去吗？ is equally correct and asks the same thing.
Which to use
They are interchangeable often enough that you can get by with 吗 alone for a long time. The difference is one of feel rather than rule: A-not-A is a touch more direct and more common in speech, and because it lays both options out it sounds slightly more like a genuine open question. 吗 can carry an expectation — 你去吗？ often implies the speaker thinks you might be.
The one place A-not-A cannot go is a sentence that already has an adverb like 很 or 也 in front of the verb, where 吗 is the only option.
你也去吗？
Nǐ yě qù ma?
Are you going too?