吗

吗 (ma, neutral tone) is the Chinese sentence-final particle that turns a statement into a yes/no question. Add it to the end of any declarative sentence and the meaning flips from 'X is true' to 'Is X true?' — 你好 'You're well' becomes 你好吗 'Are you well?' Unlike English, Chinese does not invert word order or add a 'do/does' helper to form yes/no questions; the particle 吗 does all the work. Two clarifications: first, 吗 is only for yes/no questions — for 'who / what / where / when / why' questions you use a question word and drop 吗. Second, the tone is neutral and the syllable is unstressed; written with full tone 'ma' is wrong. The character 吗 shares its right side with 妈 (mother), but the mouth radical 口 marks it as a spoken particle.

Memory hook: 口 (mouth) on the left signals 'something said'; 马 (mǎ) gives the sound. A mouth-sound that turns statements into questions.