Closed questions always start with a verb, the finite verb to more precise. While in English, we usually need an auxiliary verb (to do) to form a proper closed question, in Dutch we can do without. All it requires is inversion of the finite form and a question mark at the end of the sentence:
|Jullie staan meestal vroeg op
||You usually get up early
|Staan jullie meestal vroeg op?
||Do you usually get up early?
As you can see, the question is almost identical to the affirmative phrase. The only change is from jullie staan (affirmative) to staan jullie (question).
|Arjan is niet op haar verjaardag gekomen
||Arjan has not visited her for her birthday
|Is Arjan niet op haar verjaardag gekomen?
||Has Arjan not visited her for her birthday?
The above sentence is both a question and a negation. You can see that niet is situated between the middle and the right part: op haar verjaardag is a prepositional object, which sits at the beginning of the right part.
|Er waren geen getuigen van het ongeval
||There were no witnesses of the accident
|Waren er geen getuigen van het ongeval?
||Were there no witnesses of the accident?
Because the subject is non-specific (geen is an indefinite pronoun), we add the little word er. See also extra er at the beginning of a sentence. If we turn this type of sentence into a question, it is er that switches places with the verb, not the subject (geen getuigen).