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Light travels at a speed(速度) which is about a million times 1 . ________ than that of sound. 2. ________ one second, light trave ls about 300,000 kilometers, but sound travels only 340 meters. You can get some idea of this difference by 3. ________ the start of a running match. If you stand far away from the starter(发令员), you can see smoke 4.________ from his gun 5.________ the sound reaches your ears.
