a one-megaton bomb的用法和样例：
- Had Toutatis hit the Earth, it would have had the explosive impact of a one million megaton bomb, many times the total nuclear arsenal of the superpowers, and destroyed all life on the planet.
- How much is a one way ticket to Boston?
- How much is it for a one day pass?
- You should pay $28 for a one way ticket.
- And then, within minutes, the isolated, verdant mountains above China's most famous panda reserve exploded as if hit by a megaton bomb.