Wh- questions are also called information questions, and they are used to get information that you don’t know. Wh-questions in the past tense are formed as follows:

You can make a Wh- question to get information that is either in the subject or the predicate of your answer.

Let’s take the following answer:

Luis	talked to Gina in the garage
SUBJECT	PREDICATE

If you want to know who talked to Gina, then you’re looking for information that is in the subject of your answer. But if you want to know where they talked, then your information is in the predicate of your answer. This is important because wh- questions are formed in two different ways, depending on the part of the answer (subject or predicate) where the desired information is.