What do prepositions almost always come before?

Complete with the correct preposition: "Jenny jumped ______ her bike and rode off."

Which is correct? "The train went ______ the tunnel."

Which is correct? "It's really hot here _______ summer."

Which is correct? "Let's go _______ a walk in the park."

Which is correct? "How long has it been _______ you called your mother?"

"Everyone was there except for the manager." Which means the same as except for?

Complete the complex preposition: "The parking space in front _______ my house is reserved."

Which is a preposition?