Naturally occurring radiation varies depending on factors like local geology and altitude. People are exposed to additional radiation when they get an X-ray or fly in an airplane.
正常情况下的辐射量也随地理环境、海拔等因素变化。当受到X射线辐射或坐飞机时，人们就会受到额外辐射。
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The Ares I-X towers 327 feet (100 meters) above Launch Pad 39B, a launching site that until recently was used to fly space shuttles, and has been converted for the new booster.