Fill in the blanks with when, where, what, or how to complete the sentences

Fill in the blanks with when, where, what, or how to complete the sentences.
5.Help me decide___  to go on vacation.
6.Do you know___  to do if you are stung by a bee?
7.My husband and I are so busy these days. We don't know___  to celebrate our anniversary.
8.I want to speak better English, but I don't know___  to do that.