Pronouns + negation + the 吗 question
Mandarin pronouns are short and regular. Plurals are made by tacking on 们. Negation is just 不 placed in front of the verb. To ask a yes/no question, leave the sentence alone and stick 吗 on the end. No word order shuffling, no 'do you' helper, no question intonation rise.
Singular and plural pronouns
我 (I), 你 (you, informal), 您 (you, polite — for elders, teachers, customers), 他 (he), 她 (she), 它 (it — animals/things). Plural just adds 们: 我们 (we), 你们 (you all), 他们 (they). The thing to memorize: 他, 她, and 它 are three different characters with the same pronunciation tā. In speech, context tells you which. In writing, the radicals tell you: 他 has the 'person' radical 亻, 她 has the 'woman' radical 女, 它 has the 'roof' radical 宀.
Negation: 不 in front of the verb
不 comes directly before the verb or adjective. 我是学生。 → 我不是学生。 = I'm not a student. 她很好。 → 她不好。 = She's not well. (Note: 很 drops out under negation.) 我不是中国人。 = I'm not Chinese. There is one tone-change rule for 不: it's normally bù (4th tone), but before another 4th-tone syllable it shifts to bú. So 不是 is said bú shì, but 不好 stays bù hǎo.
吗 — the yes/no question particle
Take any statement and add 吗 to the end. 你是学生。 → 你是学生吗? = Are you a student? 她很好。 → 她很好吗? = Is she well? Word order doesn't change. Tone of voice doesn't change. To answer 'yes', repeat the verb: 是。 ('Yes [I am].') To answer 'no', negate the verb: 不是。 ('No [I'm not].') Mandarin doesn't have one universal word for 'yes' or 'no' — you echo the verb.
Putting it together
他是老师吗? = Is he a teacher? — 是,他是老师。 / 不是,他是学生。 她们是中国人吗? = Are they Chinese? — 她们不是中国人。 = They're not Chinese. 你叫王明吗? = Are you (called) Wang Ming? — 不,我叫李娜。 = No, I'm Li Na.
