The Morse code(摹斯电码)is a very useful system of signals which was devised by the inventor of the electric telegraph, Samuel F.B.Morse. He developed a code of dots and dashes(划)so that he could send messages along the telegraph wire. the dots and dashes are pulses electricity. Letters of the alphabet, numerals, the dots and dashes are pulses electricity. Letters of the alphabet, numerals, and punctuations(标点) are represented ay different combination (组合) of dots and dashes. Certain other combinations are employed to indicate (表示)Such things as End of Message or Error. The Morse code is still widely used for long distance communications by telegraph (海底电报) or radio, Radio operators c n ships often use it, and so do amateur (业余的) radio enthusiasts (好者)。 There are other ways in which message can be sent by Morse code. At sea, ships within sight of each other but out of earshot can communicate by flashing lamp. This is a searchlight with a shutter which is opened and closed to give short and long flashes. These flashes stand for the dashes of code. The Morse Code The passage mainly tells us ________.