A light-bulb moment is when you have a sudden realization about something. It's a moment of sudden inspiration, revelation, or recognition.
Light-bulb moment is an event when one suddenly understands something even if the concept had been explained several times before.
例句： President-Elect Obama said that there was not a light-bulb moment when he decided to name Hillary Clinton as Secretary of State.
Hey guys I just got an idea; yes I had a light bulb moment!