When a sentence is written in the interrogative mood, the verb form should typically be inverted or placed after the subject, and often begins with a question word (such as "what," "how," "where," "when," "who," etc.) or an auxiliary/modal verb (such as "is," "are," "do," "will," etc.). For example:
- "Is she coming to the party?"
- "Do you like coffee?"
- "What are you doing?"
In essence, the structure of the sentence alters to indicate that a question is being asked.