Who and why questions are commonly used in the simple present tense to ask about people and reasons. Who is used to refer to people, as in "Who is your best friend?" Why is used to ask for an explanation or reason, like "Why are they late?" WH-questions start with words like what, when, where, who, why and how to solicit different types of information. Prepositions like to, into, in, out of, at, towards, back and around are often used with verbs of movement to indicate direction or destination of movement. Negative statements are formed by using the word "not" after a helping verb like "is" or "are" to negate the sentence, such as