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Please answer the question below.

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Which sentence uses what correctly?

She knows what does he like.

The correct structure should be She knows what he likes, without the auxiliary verb does in the clause.

What she is watching is very interesting?

This sentence incorrectly ends with a question mark as it is not a question but a statement.

I don't understand what you mean.

Tell me what is your name.

The correct question form is What is your name? or Tell me what your name is.