The two experimenters moved a great distance from each other at night. The first opened the cover of the lantern and at the same time started the device for measuring time. The second experimenter opened his lantern as soon as he saw the light from the first lantern. The first experimenter, seeing the light from the second flashlight, stopped the time-measuring device.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.