Closed interrogative clauses are used, when a statement or a thesis shall be confirmed or negated.
Does he come for lunch today? Yes (he does).
Have you had coffee already? No (I have not).
We see, that the total value of the statement is confirmed or negated. Further, we see that the clause is formed similar to a normal statement. Only then a simple yes/no-answer is possible. As you can see - this does not make sense with open questions.
What time is it? Yes.
What is your name? No.
Which of the two books did you like best? Yes.
We usually receive closed questions by an inversion of the declarative sentence.
declarative sentence:He has bought the book.
interrogative clause: Has he bought the book?
In spoken language one can also use the declarative sentence and form the question only by intonation.
He likes Campari? This surprises me, I thought he does not drink any alcohol.
In French, we have different options to form closed interrogative clauses, as we are going to show in the following chapters.