Red light green light

Question: If green means go, yellow means slow down or caution, and red means stop. Why can't traffic lights go when they turn to green?

Question: What tastes better than it smells?

Question: What loses its head in the morning and gets it back at night?

Question: What two things can you never eat for breakfast?

Question: What asks but never answers?

Question: What can you catch but not throw?