the keyboard is the most often used as well as the most important PC output appliance .by using the keyboard ,you can type letters,numbers,marks(不仅仅是标点符号,而应该是所有的符号吧?所以我用的是符号... the keyboard is the most often used as well as the most important PC output appliance .by using the keyboard ,you can type letters,numbers,marks(不仅仅是标点符号,而应该是所有的符号吧?所以我用的是符号...