How to use 吗
Subject + 知道 / 明白 / 能告诉… + Embedded Question + 吗？
吗 asks whether the larger proposition is true. A question word can appear in that proposition when it belongs to an embedded question, rather than directly asking the listener for the missing information. Verbs about knowing, understanding, asking, or telling commonly introduce this inner clause. The outer question checks knowledge, understanding, or willingness to respond.
Keep ordinary Chinese word order inside the embedded clause. There is no English-style inversion to add. The distinction is between directly asking what something is and asking whether someone knows what it is. The first normally needs only the question word; the second can legitimately end in 吗 because it has a separate yes-no layer.
Examples with pinyin and English
这是什么？
What is this?
你知道这是什么吗？
Do you know what this is?
他是谁？
Who is he?
你知道他是谁吗？
Do you know who he is?
What to remember
- Identify the outer yes-no question.
- Keep statement order in the embedded clause.
- 吗 applies to the whole sentence.
Practise the pattern
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Source and editorial notes
Explanation rewritten for Laowai. Examples are adapted from the Laowai English grammar curriculum, with editorial corrections where needed. The original curriculum credits AllSet Learning’s Chinese Grammar Wiki as used with permission. Read the retained source credits.
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