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.
1.I have so many ingredients, but I don't know___to make!
2.This city is so expensive. I don't know___to live.
3.I want to marry my girlfriend, but I'm not sure___to propose.
4.Help! My room is infested with ants. I don't know___to do!